X-Git-Url: https://git.saurik.com/apple/security.git/blobdiff_plain/c38e3ce98599a410a47dc10253faa4d5830f13b2..427c49bcad63d042b29ada2ac27e3dfc4845c779:/sec/SOSCircle/SecureObjectSync/SOSCircle.c?ds=sidebyside

diff --git a/sec/SOSCircle/SecureObjectSync/SOSCircle.c b/sec/SOSCircle/SecureObjectSync/SOSCircle.c
new file mode 100644
index 00000000..9475fc64
--- /dev/null
+++ b/sec/SOSCircle/SecureObjectSync/SOSCircle.c
@@ -0,0 +1,1171 @@
+/*
+ * Created by Michael Brouwer on 6/22/12.
+ * Copyright 2012 Apple Inc. All Rights Reserved.
+ */
+
+/*
+ * SOSCircle.c -  Implementation of the secure object syncing transport
+ */
+
+#include <AssertMacros.h>
+
+#include <CoreFoundation/CFArray.h>
+#include <SecureObjectSync/SOSCircle.h>
+#include <SecureObjectSync/SOSCloudCircleInternal.h>
+#include <SecureObjectSync/SOSInternal.h>
+#include <SecureObjectSync/SOSEngine.h>
+#include <SecureObjectSync/SOSPeer.h>
+#include <CoreFoundation/CoreFoundation.h>
+#include <Security/SecFramework.h>
+
+#include <Security/SecKey.h>
+#include <Security/SecKeyPriv.h>
+
+#include <utilities/SecCFWrappers.h>
+//#include "ckdUtilities.h"
+
+#include <utilities/der_plist.h>
+#include <utilities/der_plist_internal.h>
+
+#include <corecrypto/ccder.h>
+#include <corecrypto/ccdigest.h>
+#include <corecrypto/ccsha2.h>
+
+#include <stdlib.h>
+#include <assert.h>
+
+enum {
+    kOnlyCompatibleVersion = 1, // Sometime in the future this name will be improved to reflect history.
+    
+    kAlwaysIncompatibleVersion = UINT64_MAX,
+};
+
+struct __OpaqueSOSCircle {
+    CFRuntimeBase _base;
+    
+    CFStringRef name;
+    CFNumberRef generation;
+    CFMutableArrayRef peers;
+    CFMutableArrayRef applicants;
+    CFMutableArrayRef rejected_applicants;
+
+    CFMutableDictionaryRef signatures;
+};
+
+CFGiblisWithCompareFor(SOSCircle);
+
+// Move the next 2 lines to SOSPeer if we need it.
+static void SOSPeerRelease(CFAllocatorRef allocator, const void *value) {
+    SOSPeerDispose((SOSPeerRef)value);
+}
+
+static const CFDictionaryValueCallBacks dispose_peer_callbacks = { .release = SOSPeerRelease };
+
+SOSCircleRef SOSCircleCreate(CFAllocatorRef allocator, CFStringRef name, CFErrorRef *error) {
+    SOSCircleRef c = CFTypeAllocate(SOSCircle, struct __OpaqueSOSCircle, allocator);
+    int64_t gen = 1;
+
+    assert(name);
+    
+    c->name = CFStringCreateCopy(allocator, name);
+    c->generation = CFNumberCreate(allocator, kCFNumberSInt64Type, &gen);
+    c->peers = CFArrayCreateMutableForCFTypes(allocator);
+    c->applicants = CFArrayCreateMutableForCFTypes(allocator);
+    c->rejected_applicants = CFArrayCreateMutableForCFTypes(allocator);
+    c->signatures = CFDictionaryCreateMutableForCFTypes(allocator);
+
+    return c;
+}
+
+static CFNumberRef SOSCircleGenerationCopy(CFNumberRef generation) {
+    int64_t value;
+    CFAllocatorRef allocator = CFGetAllocator(generation);
+    CFNumberGetValue(generation, kCFNumberSInt64Type, &value);
+    return CFNumberCreate(allocator, kCFNumberSInt64Type, &value);
+}
+
+SOSCircleRef SOSCircleCopyCircle(CFAllocatorRef allocator, SOSCircleRef otherCircle, CFErrorRef *error)
+{
+    SOSCircleRef c = CFTypeAllocate(SOSCircle, struct __OpaqueSOSCircle, allocator);
+
+    assert(otherCircle);
+    c->name = CFStringCreateCopy(allocator, otherCircle->name);
+    c->generation = SOSCircleGenerationCopy(otherCircle->generation);
+    c->peers = CFArrayCreateMutableCopy(allocator, 0, otherCircle->peers);
+    c->applicants = CFArrayCreateMutableCopy(allocator, 0, otherCircle->applicants);
+    c->rejected_applicants = CFArrayCreateMutableCopy(allocator, 0, otherCircle->rejected_applicants);
+    c->signatures = CFDictionaryCreateMutableCopy(allocator, 0, otherCircle->signatures);
+    
+    return c;
+}
+
+static inline
+void SOSCircleAssertStable(SOSCircleRef circle)
+{
+    assert(circle);
+    assert(circle->name);
+    assert(circle->generation);
+    assert(circle->peers);
+    assert(circle->applicants);
+    assert(circle->rejected_applicants);
+    assert(circle->signatures);
+}
+
+static inline
+SOSCircleRef SOSCircleConvertAndAssertStable(CFTypeRef circleAsType)
+{
+    if (CFGetTypeID(circleAsType) != SOSCircleGetTypeID())
+        return NULL;
+
+    SOSCircleRef circle = (SOSCircleRef) circleAsType;
+
+    SOSCircleAssertStable(circle);
+
+    return circle;
+}
+
+
+static Boolean SOSCircleCompare(CFTypeRef lhs, CFTypeRef rhs) {
+    if (CFGetTypeID(lhs) != SOSCircleGetTypeID()
+     || CFGetTypeID(rhs) != SOSCircleGetTypeID())
+        return false;
+
+    SOSCircleRef left = SOSCircleConvertAndAssertStable(lhs);
+    SOSCircleRef right = SOSCircleConvertAndAssertStable(rhs);
+
+    // TODO: we should be doing set equality for peers and applicants.
+    return NULL != left && NULL != right
+        && CFEqual(left->generation, right->generation)
+        && CFEqual(left->peers, right->peers)
+        && CFEqual(left->applicants, right->applicants)
+        && CFEqual(left->rejected_applicants, right->rejected_applicants)
+        && CFEqual(left->signatures, right->signatures);
+}
+
+
+static bool SOSCircleDigestArray(const struct ccdigest_info *di, CFMutableArrayRef array, void *hash_result, CFErrorRef *error)
+{
+    __block bool success = true;
+    ccdigest_di_decl(di, array_digest);
+    const void * a_digest = array_digest;
+
+    ccdigest_init(di, array_digest);
+    CFArraySortValues(array, CFRangeMake(0, CFArrayGetCount(array)), SOSPeerInfoCompareByID, SOSPeerCmpPubKeyHash);
+    CFArrayForEach(array, ^(const void *peer) {
+        if (!SOSPeerInfoUpdateDigestWithPublicKeyBytes((SOSPeerInfoRef)peer, di, a_digest, error))
+            success = false;
+    });
+    ccdigest_final(di, array_digest, hash_result);
+
+    return success;
+}
+
+static bool SOSCircleHash(const struct ccdigest_info *di, SOSCircleRef circle, void *hash_result, CFErrorRef *error) {
+    ccdigest_di_decl(di, circle_digest);
+    ccdigest_init(di, circle_digest);
+    int64_t gen = SOSCircleGetGenerationSint(circle);
+    ccdigest_update(di, circle_digest, sizeof(gen), &gen);
+    
+    SOSCircleDigestArray(di, circle->peers, hash_result, error);
+    ccdigest_update(di, circle_digest, di->output_size, hash_result);
+    ccdigest_final(di, circle_digest, hash_result);
+    return true;
+}
+
+static bool SOSCircleSetSignature(SOSCircleRef circle, SecKeyRef pubkey, CFDataRef signature, CFErrorRef *error) {
+    bool result = false;
+    
+    CFStringRef pubKeyID = SOSCopyIDOfKey(pubkey, error);
+    require_quiet(pubKeyID, fail);
+    CFDictionarySetValue(circle->signatures, pubKeyID, signature);
+    result = true;
+
+fail:
+    CFReleaseSafe(pubKeyID);
+    return result;
+}
+
+static bool SOSCircleRemoveSignatures(SOSCircleRef circle, CFErrorRef *error) {
+    CFDictionaryRemoveAllValues(circle->signatures);
+    return true;
+}
+
+static CFDataRef SOSCircleGetSignature(SOSCircleRef circle, SecKeyRef pubkey, CFErrorRef *error) {    
+    CFStringRef pubKeyID = SOSCopyIDOfKey(pubkey, error);
+    CFDataRef result = NULL;
+    require_quiet(pubKeyID, fail);
+
+    CFTypeRef value = (CFDataRef)CFDictionaryGetValue(circle->signatures, pubKeyID);
+    
+    if (isData(value)) result = (CFDataRef) value;
+
+fail:
+    CFReleaseSafe(pubKeyID);
+    return result;
+}
+
+bool SOSCircleSign(SOSCircleRef circle, SecKeyRef privKey, CFErrorRef *error) {
+    if (!privKey) return false; // Really assertion but not always true for now.
+    CFAllocatorRef allocator = CFGetAllocator(circle);
+    uint8_t tmp[4096];
+    size_t tmplen = 4096;
+    const struct ccdigest_info *di = ccsha256_di();
+    uint8_t hash_result[di->output_size];
+    
+    SOSCircleHash(di, circle, hash_result, error);
+    OSStatus stat =  SecKeyRawSign(privKey, kSecPaddingNone, hash_result, di->output_size, tmp, &tmplen);
+    if(stat) {
+        // TODO - Create a CFErrorRef;
+        secerror("Bad Circle SecKeyRawSign, stat: %ld", (long)stat);
+        SOSCreateError(kSOSErrorBadFormat, CFSTR("Bad Circle SecKeyRawSign"), (error != NULL) ? *error : NULL, error);
+        return false;
+    };
+    CFDataRef signature = CFDataCreate(allocator, tmp, tmplen);
+    SecKeyRef publicKey = SecKeyCreatePublicFromPrivate(privKey);
+    SOSCircleSetSignature(circle, publicKey, signature, error);
+    CFReleaseNull(publicKey);
+    CFRelease(signature);
+    return true;
+}
+
+bool SOSCircleVerifySignatureExists(SOSCircleRef circle, SecKeyRef pubKey, CFErrorRef *error) {
+    if(!pubKey) {
+        // TODO ErrorRef
+        secerror("SOSCircleVerifySignatureExists no pubKey");
+        SOSCreateError(kSOSErrorBadFormat, CFSTR("SOSCircleVerifySignatureExists no pubKey"), (error != NULL) ? *error : NULL, error);
+        return false;
+    }
+    CFDataRef signature = SOSCircleGetSignature(circle, pubKey, error);
+    return NULL != signature;
+}
+
+bool SOSCircleVerify(SOSCircleRef circle, SecKeyRef pubKey, CFErrorRef *error) {
+    const struct ccdigest_info *di = ccsha256_di();
+    uint8_t hash_result[di->output_size];
+    
+    SOSCircleHash(di, circle, hash_result, error);
+
+    CFDataRef signature = SOSCircleGetSignature(circle, pubKey, error);
+    if(!signature) return false;
+
+    return SecKeyRawVerify(pubKey, kSecPaddingNone, hash_result, di->output_size,
+                           CFDataGetBytePtr(signature), CFDataGetLength(signature)) == errSecSuccess;
+}
+
+bool SOSCircleVerifyPeerSigned(SOSCircleRef circle, SOSPeerInfoRef peer, CFErrorRef *error) {
+    SecKeyRef pub_key = SOSPeerInfoCopyPubKey(peer);
+    bool result = SOSCircleVerify(circle, pub_key, error);
+    CFReleaseSafe(pub_key);
+    return result;
+}
+
+
+static CFIndex CFArrayRemoveAllPassing(CFMutableArrayRef array, bool (^test)(const void *) ){
+    CFIndex numberRemoved = 0;
+    
+    CFIndex position =  0;
+    while (position < CFArrayGetCount(array) && !test(CFArrayGetValueAtIndex(array, position)))
+        ++position;
+    
+    while (position < CFArrayGetCount(array)) {
+        CFArrayRemoveValueAtIndex(array, position);
+        ++numberRemoved;
+        while (position < CFArrayGetCount(array) && !test(CFArrayGetValueAtIndex(array, position)))
+            ++position;
+    }
+    
+    return numberRemoved;
+}
+
+static CFIndex CFArrayRemoveAllWithMatchingID(CFMutableArrayRef array, SOSPeerInfoRef peerInfo) {
+    CFStringRef peer_id = SOSPeerInfoGetPeerID(peerInfo);
+    
+    return CFArrayRemoveAllPassing(array,  ^ bool (const void *element) {
+        SOSPeerInfoRef peer = (SOSPeerInfoRef) element;
+        
+        return CFEqual(peer_id, SOSPeerInfoGetPeerID(peer));
+    });
+}
+
+static void SOSCircleRejectNonValidApplicants(SOSCircleRef circle, SecKeyRef pubkey) {
+    CFArrayRef applicants = SOSCircleCopyApplicants(circle, NULL);
+    CFArrayForEach(applicants, ^(const void *value) {
+        SOSPeerInfoRef pi = (SOSPeerInfoRef) value;
+        if(!SOSPeerInfoApplicationVerify(pi, pubkey, NULL)) {
+            CFArrayRemoveAllWithMatchingID(circle->applicants, pi);
+            CFArrayAppendValue(circle->rejected_applicants, pi);
+        }
+    });
+}
+
+bool SOSCircleGenerationSign(SOSCircleRef circle, SecKeyRef user_approver, SOSFullPeerInfoRef peerinfo, CFErrorRef *error) {
+    
+    SecKeyRef ourKey = SOSFullPeerInfoCopyDeviceKey(peerinfo, error);
+    require_quiet(ourKey, fail);
+    
+    SOSCircleRemoveRetired(circle, error); // Prune off retirees since we're signing this one
+    CFArrayRemoveAllValues(circle->rejected_applicants); // Dump rejects so we clean them up sometime.
+    SOSCircleRejectNonValidApplicants(circle, SecKeyCreatePublicFromPrivate(user_approver));
+    SOSCircleGenerationIncrement(circle);
+    require_quiet(SOSCircleRemoveSignatures(circle, error), fail);
+    require_quiet(SOSCircleSign(circle, user_approver, error), fail);
+    require_quiet(SOSCircleSign(circle, ourKey, error), fail);
+    
+    CFReleaseNull(ourKey);
+    return true;
+    
+fail:
+    CFReleaseNull(ourKey);
+    return false;
+}
+
+
+bool SOSCircleConcordanceSign(SOSCircleRef circle, SOSFullPeerInfoRef peerinfo, CFErrorRef *error) {
+    bool success = false;
+    SecKeyRef ourKey = SOSFullPeerInfoCopyDeviceKey(peerinfo, error);
+    require_quiet(ourKey, exit);
+    
+    success = SOSCircleSign(circle, ourKey, error);
+
+exit:
+    CFReleaseNull(ourKey);
+    return success;
+}
+
+static inline SOSConcordanceStatus CheckPeerStatus(SOSCircleRef circle, SOSPeerInfoRef peer, CFErrorRef *error) {
+    SOSConcordanceStatus result = kSOSConcordanceNoPeer;
+    SecKeyRef pubKey = SOSPeerInfoCopyPubKey(peer);
+
+    require_action_quiet(SOSCircleHasActivePeer(circle, peer, error), exit, result = kSOSConcordanceNoPeer);
+    require_action_quiet(SOSCircleVerifySignatureExists(circle, pubKey, error), exit, result = kSOSConcordanceNoPeerSig);
+    require_action_quiet(SOSCircleVerify(circle, pubKey, error), exit, result = kSOSConcordanceBadPeerSig);
+    
+    result = kSOSConcordanceTrusted;
+    
+exit:
+    CFReleaseNull(pubKey);
+    return result;
+}
+
+static inline SOSConcordanceStatus CombineStatus(SOSConcordanceStatus status1, SOSConcordanceStatus status2)
+{
+    if (status1 == kSOSConcordanceTrusted || status2 == kSOSConcordanceTrusted)
+        return kSOSConcordanceTrusted;
+    
+    if (status1 == kSOSConcordanceBadPeerSig || status2 == kSOSConcordanceBadPeerSig)
+        return kSOSConcordanceBadPeerSig;
+    
+    if (status1 == kSOSConcordanceNoPeerSig || status2 == kSOSConcordanceNoPeerSig)
+        return kSOSConcordanceNoPeerSig;
+
+    return status1;
+}
+
+static inline bool SOSCircleIsEmpty(SOSCircleRef circle) {
+    return SOSCircleCountPeers(circle) == 0;
+}
+
+static inline bool SOSCircleIsOffering(SOSCircleRef circle) {
+    return SOSCircleCountPeers(circle) == 1;
+}
+
+static inline bool SOSCircleIsResignOffering(SOSCircleRef circle, SecKeyRef pubkey) {
+    return SOSCircleCountActiveValidPeers(circle, pubkey) == 1;
+}
+
+static inline SOSConcordanceStatus GetSignersStatus(SOSCircleRef signers_circle, SOSCircleRef status_circle,
+                                                    SecKeyRef user_pubKey, SOSPeerInfoRef exclude, CFErrorRef *error) {
+    CFStringRef excluded_id = exclude ? SOSPeerInfoGetPeerID(exclude) : NULL;
+
+    __block SOSConcordanceStatus status = kSOSConcordanceNoPeer;
+    SOSCircleForEachActiveValidPeer(signers_circle, user_pubKey, ^(SOSPeerInfoRef peer) {
+        SOSConcordanceStatus peerStatus = CheckPeerStatus(status_circle, peer, error);
+
+        if (peerStatus == kSOSConcordanceNoPeerSig &&
+            (CFEqualSafe(SOSPeerInfoGetPeerID(peer), excluded_id) || SOSPeerInfoIsCloudIdentity(peer)))
+            peerStatus = kSOSConcordanceNoPeer;
+
+        status = CombineStatus(status, peerStatus); // TODO: Use multiple error gathering.
+    });
+
+    return status;
+}
+
+static inline bool isOlderGeneration(SOSCircleRef current, SOSCircleRef proposed) {
+    return CFNumberCompare(current->generation, proposed->generation, NULL) == kCFCompareGreaterThan;
+}
+
+bool SOSCircleSharedTrustedPeers(SOSCircleRef current, SOSCircleRef proposed, SOSPeerInfoRef me) {
+    __block bool retval = false;
+    SOSCircleForEachPeer(current, ^(SOSPeerInfoRef peer) {
+        if(!CFEqual(me, peer) && SOSCircleHasPeer(proposed, peer, NULL)) retval = true;
+    });
+    return retval;
+}
+
+static void SOSCircleUpgradePeersByCircle(SOSCircleRef known_circle, SOSCircleRef proposed_circle) {
+    SOSCircleForEachPeer(known_circle, ^(SOSPeerInfoRef known_peer) {
+        SOSPeerInfoRef proposed_peer = SOSCircleCopyPeerInfo(proposed_circle, SOSPeerInfoGetPeerID(known_peer), NULL);
+        if(proposed_peer && CFEqualSafe(proposed_peer, known_peer) != 0) {
+            SOSCircleUpdatePeerInfo(known_circle, proposed_peer);
+        }
+    });
+}
+
+SOSConcordanceStatus SOSCircleConcordanceTrust(SOSCircleRef known_circle, SOSCircleRef proposed_circle,
+                                               SecKeyRef known_pubkey, SecKeyRef user_pubkey,
+                                               SOSPeerInfoRef exclude, CFErrorRef *error) {
+    
+    if(user_pubkey == NULL) {
+        SOSCreateError(kSOSErrorPublicKeyAbsent, CFSTR("Concordance with no public key"), NULL, error);
+        return kSOSConcordanceNoUserKey; //TODO: - needs to return an error
+    }
+
+    if (SOSCircleIsEmpty(proposed_circle)) {
+        return kSOSConcordanceTrusted;
+    }
+    
+    if(!SOSCircleVerifySignatureExists(proposed_circle, user_pubkey, error)) {
+        SOSCreateError(kSOSErrorBadSignature, CFSTR("No public signature"), (error != NULL) ? *error : NULL, error);
+        return kSOSConcordanceNoUserSig;
+    }
+    
+    if(!SOSCircleVerify(proposed_circle, user_pubkey, error)) {
+        SOSCreateError(kSOSErrorBadSignature, CFSTR("Bad public signature"), (error != NULL) ? *error : NULL, error);
+        return kSOSConcordanceBadUserSig;
+    }
+
+    if (SOSCircleIsEmpty(known_circle) || SOSCircleIsOffering(proposed_circle)) {
+        return GetSignersStatus(proposed_circle, proposed_circle, user_pubkey, NULL, error);
+    }
+
+    if(isOlderGeneration(known_circle, proposed_circle)) {
+        SOSCreateError(kSOSErrorReplay, CFSTR("Bad generation"), NULL, error);
+        return kSOSConcordanceGenOld;
+    }
+    
+    
+    if(!SOSCircleVerify(known_circle, user_pubkey, error)) {
+        SOSCircleUpgradePeersByCircle(known_circle, proposed_circle);
+    }
+    
+    if(known_pubkey == NULL) known_pubkey = user_pubkey;
+    if(!SOSCircleVerify(known_circle, known_pubkey, error)) known_pubkey = user_pubkey;
+    return GetSignersStatus(known_circle, proposed_circle, known_pubkey, exclude, error);
+}
+
+
+static const uint8_t* der_decode_mutable_dictionary(CFAllocatorRef allocator, CFOptionFlags mutability,
+                                                    CFMutableDictionaryRef* dictionary, CFErrorRef *error,
+                                                    const uint8_t* der, const uint8_t *der_end)
+{
+    CFDictionaryRef theDict;
+    const uint8_t* result = der_decode_dictionary(allocator, mutability, &theDict, error, der, der_end);
+
+    if (result != NULL)
+        *dictionary = (CFMutableDictionaryRef)theDict;
+
+    return result;
+}
+
+SOSCircleRef SOSCircleCreateFromDER(CFAllocatorRef allocator, CFErrorRef* error,
+                                      const uint8_t** der_p, const uint8_t *der_end) {
+    SOSCircleRef cir = CFTypeAllocate(SOSCircle, struct __OpaqueSOSCircle, allocator);
+
+    const uint8_t *sequence_end;
+
+    cir->name = NULL;
+    cir->generation = NULL;
+    cir->peers = NULL;
+    cir->applicants = NULL;
+    cir->rejected_applicants = NULL;
+    cir->signatures = NULL;
+
+    *der_p = ccder_decode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, &sequence_end, *der_p, der_end);
+    require_action_quiet(sequence_end != NULL, fail,
+                         SOSCreateError(kSOSErrorBadFormat, CFSTR("Bad Circle DER"), (error != NULL) ? *error : NULL, error));
+    
+    // Version first.
+    uint64_t version = 0;
+    *der_p = ccder_decode_uint64(&version, *der_p, der_end);
+    
+    require_action_quiet(version == kOnlyCompatibleVersion, fail,
+                         SOSCreateError(kSOSErrorIncompatibleCircle, CFSTR("Bad Circle Version"), NULL, error));
+
+    *der_p = der_decode_string(allocator, 0, &cir->name, error, *der_p, sequence_end);
+    *der_p = der_decode_number(allocator, 0, &cir->generation, error, *der_p, sequence_end);
+
+    cir->peers = SOSPeerInfoArrayCreateFromDER(allocator, error, der_p, sequence_end);
+    cir->applicants = SOSPeerInfoArrayCreateFromDER(allocator, error, der_p, sequence_end);
+    cir->rejected_applicants = SOSPeerInfoArrayCreateFromDER(allocator, error, der_p, sequence_end);
+
+    *der_p = der_decode_mutable_dictionary(allocator, kCFPropertyListMutableContainersAndLeaves,
+                                           &cir->signatures, error, *der_p, sequence_end);
+
+    require_action_quiet(*der_p == sequence_end, fail,
+                         SOSCreateError(kSOSErrorBadFormat, CFSTR("Bad Circle DER"), (error != NULL) ? *error : NULL, error));
+
+    return cir;
+    
+fail:
+    CFReleaseNull(cir);
+    return NULL;
+}
+
+SOSCircleRef SOSCircleCreateFromData(CFAllocatorRef allocator, CFDataRef circleData, CFErrorRef *error)
+{    
+    size_t size = CFDataGetLength(circleData);
+    const uint8_t *der = CFDataGetBytePtr(circleData);
+    SOSCircleRef inflated = SOSCircleCreateFromDER(allocator, error, &der, der + size);
+    return inflated;
+}
+
+size_t SOSCircleGetDEREncodedSize(SOSCircleRef cir, CFErrorRef *error) {
+    SOSCircleAssertStable(cir);
+    size_t total_payload = 0;
+
+    require_quiet(accumulate_size(&total_payload, ccder_sizeof_uint64(kOnlyCompatibleVersion)),                        fail);
+    require_quiet(accumulate_size(&total_payload, der_sizeof_string(cir->name, error)),                                fail);
+    require_quiet(accumulate_size(&total_payload, der_sizeof_number(cir->generation, error)),                          fail);
+    require_quiet(accumulate_size(&total_payload, SOSPeerInfoArrayGetDEREncodedSize(cir->peers, error)),               fail);
+    require_quiet(accumulate_size(&total_payload, SOSPeerInfoArrayGetDEREncodedSize(cir->applicants, error)),          fail);
+    require_quiet(accumulate_size(&total_payload, SOSPeerInfoArrayGetDEREncodedSize(cir->rejected_applicants, error)), fail);
+    require_quiet(accumulate_size(&total_payload, der_sizeof_dictionary((CFDictionaryRef) cir->signatures, error)),    fail);
+
+    return ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE, total_payload);
+    
+fail:
+    SecCFDERCreateError(kSecDERErrorUnknownEncoding, CFSTR("don't know how to encode"), NULL, error);
+    return 0;
+}
+
+uint8_t* SOSCircleEncodeToDER(SOSCircleRef cir, CFErrorRef* error, const uint8_t* der, uint8_t* der_end) {
+    SOSCircleAssertStable(cir);
+
+    return ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
+           ccder_encode_uint64(kOnlyCompatibleVersion, der,
+           der_encode_string(cir->name, error, der,
+           der_encode_number(cir->generation, error, der,
+           SOSPeerInfoArrayEncodeToDER(cir->peers, error, der,
+           SOSPeerInfoArrayEncodeToDER(cir->applicants, error, der,
+           SOSPeerInfoArrayEncodeToDER(cir->rejected_applicants, error, der,
+           der_encode_dictionary((CFDictionaryRef) cir->signatures, error, der, der_end))))))));
+}
+
+CFDataRef SOSCircleCreateIncompatibleCircleDER(CFErrorRef* error)
+{
+    size_t total_payload = 0;
+    size_t encoded_size = 0;
+    uint8_t* der = 0;
+    uint8_t* der_end = 0;
+    CFMutableDataRef result = NULL;
+    
+    require_quiet(accumulate_size(&total_payload, ccder_sizeof_uint64(kAlwaysIncompatibleVersion)), fail);
+    
+    encoded_size = ccder_sizeof(CCDER_CONSTRUCTED_SEQUENCE, total_payload);
+
+    result = CFDataCreateMutableWithScratch(kCFAllocatorDefault, encoded_size);
+    
+    der = CFDataGetMutableBytePtr(result);
+    der_end = der + CFDataGetLength(result);
+    
+    der_end = ccder_encode_constructed_tl(CCDER_CONSTRUCTED_SEQUENCE, der_end, der,
+              ccder_encode_uint64(kAlwaysIncompatibleVersion, der, der_end));
+ 
+fail:
+    if (der == NULL || der != der_end)
+        CFReleaseNull(result);
+
+    return result;
+}
+
+
+CFDataRef SOSCircleCopyEncodedData(SOSCircleRef circle, CFAllocatorRef allocator, CFErrorRef *error)
+{
+    size_t size = SOSCircleGetDEREncodedSize(circle, error);
+    if (size == 0)
+        return NULL;
+    uint8_t buffer[size];
+    uint8_t* start = SOSCircleEncodeToDER(circle, error, buffer, buffer + sizeof(buffer));
+    CFDataRef result = CFDataCreate(kCFAllocatorDefault, start, size);
+    return result;
+}
+
+static void SOSCircleDestroy(CFTypeRef aObj) {
+    SOSCircleRef c = (SOSCircleRef) aObj;
+
+    CFReleaseNull(c->name);
+    CFReleaseNull(c->generation);
+    CFReleaseNull(c->peers);
+    CFReleaseNull(c->applicants);
+    CFReleaseNull(c->rejected_applicants);
+    CFReleaseNull(c->signatures);
+}
+
+static CFStringRef SOSCircleCopyDescription(CFTypeRef aObj) {
+    SOSCircleRef c = (SOSCircleRef) aObj;
+    
+    SOSCircleAssertStable(c);
+
+    return CFStringCreateWithFormat(NULL, NULL,
+                                    CFSTR("<SOSCircle@%p: [ \nName: %@, \nPeers: %@,\nApplicants: %@,\nRejects: %@,\nSignatures: %@\n ] >"),
+                                    c, c->name, c->peers, c->applicants, c->rejected_applicants, c->signatures);
+}
+
+CFStringRef SOSCircleGetName(SOSCircleRef circle) {
+    assert(circle);
+    assert(circle->name);
+    return circle->name;
+}
+
+const char *SOSCircleGetNameC(SOSCircleRef circle) {
+    CFStringRef name = SOSCircleGetName(circle);
+    if (!name)
+        return strdup("");
+    return CFStringToCString(name);
+}
+
+CFNumberRef SOSCircleGetGeneration(SOSCircleRef circle) {
+    assert(circle);
+    assert(circle->generation);
+    return circle->generation;
+}
+
+int64_t SOSCircleGetGenerationSint(SOSCircleRef circle) {
+    CFNumberRef gen = SOSCircleGetGeneration(circle);
+    int64_t value;
+    if(!gen) return 0;
+    CFNumberGetValue(gen, kCFNumberSInt64Type, &value);
+    return value;
+}
+
+void SOSCircleGenerationIncrement(SOSCircleRef circle) {
+    CFAllocatorRef allocator = CFGetAllocator(circle->generation);
+    int64_t value = SOSCircleGetGenerationSint(circle);
+    value++;
+    circle->generation = CFNumberCreate(allocator, kCFNumberSInt64Type, &value);
+}
+
+int SOSCircleCountPeers(SOSCircleRef circle) {
+    SOSCircleAssertStable(circle);
+    __block int count = 0;
+    SOSCircleForEachPeer(circle, ^(SOSPeerInfoRef peer) {
+        ++count;
+    });
+    return count;
+}
+
+int SOSCircleCountActivePeers(SOSCircleRef circle) {
+    SOSCircleAssertStable(circle);
+    __block int count = 0;
+    SOSCircleForEachActivePeer(circle, ^(SOSPeerInfoRef peer) {
+        ++count;
+    });
+    return count;
+}
+
+int SOSCircleCountActiveValidPeers(SOSCircleRef circle, SecKeyRef pubkey) {
+    SOSCircleAssertStable(circle);
+    __block int count = 0;
+    SOSCircleForEachActiveValidPeer(circle, pubkey, ^(SOSPeerInfoRef peer) {
+        ++count;
+    });
+    return count;
+}
+
+int SOSCircleCountRetiredPeers(SOSCircleRef circle) {
+    SOSCircleAssertStable(circle);
+    __block int count = 0;
+    SOSCircleForEachRetiredPeer(circle, ^(SOSPeerInfoRef peer) {
+        ++count;
+    });
+    return count;
+}
+
+int SOSCircleCountApplicants(SOSCircleRef circle) {
+    SOSCircleAssertStable(circle);
+    
+    return (int)CFArrayGetCount(circle->applicants);
+}
+
+bool SOSCircleHasApplicant(SOSCircleRef circle, SOSPeerInfoRef peerInfo, CFErrorRef *error) {
+    SOSCircleAssertStable(circle);
+    
+    return CFArrayHasValueMatching(circle->applicants, ^bool(const void *value) {
+        return SOSPeerInfoCompareByID(value, peerInfo, NULL) == 0;
+    });
+}
+
+CFMutableArrayRef SOSCircleCopyApplicants(SOSCircleRef circle, CFAllocatorRef allocator) {
+    SOSCircleAssertStable(circle);
+    
+    return CFArrayCreateMutableCopy(allocator, 0, circle->applicants);
+}
+
+int SOSCircleCountRejectedApplicants(SOSCircleRef circle) {
+    SOSCircleAssertStable(circle);
+    
+    return (int)CFArrayGetCount(circle->rejected_applicants);
+}
+
+bool SOSCircleHasRejectedApplicant(SOSCircleRef circle, SOSPeerInfoRef peerInfo, CFErrorRef *error) {
+    SOSCircleAssertStable(circle);
+
+    return CFArrayHasValueMatching(circle->rejected_applicants, ^bool(const void *value) {
+        return SOSPeerInfoCompareByID(value, peerInfo, NULL) == 0;
+    });
+}
+
+SOSPeerInfoRef SOSCircleCopyRejectedApplicant(SOSCircleRef circle, SOSPeerInfoRef peerInfo, CFErrorRef *error) {
+    SOSCircleAssertStable(circle);
+    return (SOSPeerInfoRef) CFArrayGetValueMatching(circle->rejected_applicants, ^bool(const void *value) {
+        return SOSPeerInfoCompareByID(value, peerInfo, NULL) == 0;
+    });
+}
+
+CFMutableArrayRef SOSCircleCopyRejectedApplicants(SOSCircleRef circle, CFAllocatorRef allocator) {
+    SOSCircleAssertStable(circle);
+    
+    return CFArrayCreateMutableCopy(allocator, 0, circle->rejected_applicants);
+}
+
+
+bool SOSCircleHasPeerWithID(SOSCircleRef circle, CFStringRef peerid, CFErrorRef *error) {
+    SOSCircleAssertStable(circle);
+    __block bool found = false;
+    SOSCircleForEachPeer(circle, ^(SOSPeerInfoRef peer) {
+        if(peerid && peer && CFEqualSafe(peerid, SOSPeerInfoGetPeerID(peer))) found = true;
+    });
+    return found;
+}
+
+bool SOSCircleHasPeer(SOSCircleRef circle, SOSPeerInfoRef peerInfo, CFErrorRef *error) {
+    return SOSCircleHasPeerWithID(circle, SOSPeerInfoGetPeerID(peerInfo), error);
+}
+
+bool SOSCircleHasActivePeerWithID(SOSCircleRef circle, CFStringRef peerid, CFErrorRef *error) {
+    SOSCircleAssertStable(circle);
+    __block bool found = false;
+    SOSCircleForEachActivePeer(circle, ^(SOSPeerInfoRef peer) {
+        if(peerid && peer && CFEqualSafe(peerid, SOSPeerInfoGetPeerID(peer))) found = true;
+    });
+    return found;
+}
+
+bool SOSCircleHasActivePeer(SOSCircleRef circle, SOSPeerInfoRef peerInfo, CFErrorRef *error) {
+    if(!peerInfo) return false;
+    return SOSCircleHasActivePeerWithID(circle, SOSPeerInfoGetPeerID(peerInfo), error);
+}
+
+
+
+bool SOSCircleResetToEmpty(SOSCircleRef circle, CFErrorRef *error) {
+    CFArrayRemoveAllValues(circle->applicants);
+    CFArrayRemoveAllValues(circle->peers);
+    CFDictionaryRemoveAllValues(circle->signatures);
+
+    return true;
+}
+
+bool SOSCircleResetToOffering(SOSCircleRef circle, SecKeyRef user_privkey, SOSFullPeerInfoRef requestor, CFErrorRef *error){
+
+    return SOSCircleResetToEmpty(circle, error)
+        && SOSCircleRequestAdmission(circle, user_privkey, requestor, error)
+        && SOSCircleAcceptRequest(circle, user_privkey, requestor, SOSFullPeerInfoGetPeerInfo(requestor), error);
+}
+
+CFIndex SOSCircleRemoveRetired(SOSCircleRef circle, CFErrorRef *error) {
+    CFIndex n = CFArrayRemoveAllPassing(circle->peers,  ^ bool (const void *element) {
+        SOSPeerInfoRef peer = (SOSPeerInfoRef) element;
+        
+        return SOSPeerInfoIsRetirementTicket(peer);
+    });
+    
+    return n;
+}
+
+static bool SOSCircleRecordAdmission(SOSCircleRef circle, SecKeyRef user_pubkey, SOSFullPeerInfoRef requestor, CFErrorRef *error) {
+    SOSCircleAssertStable(circle);
+    
+    bool isPeer = SOSCircleHasPeer(circle, SOSFullPeerInfoGetPeerInfo(requestor), error);
+    
+    require_action_quiet(!isPeer, fail, SOSCreateError(kSOSErrorAlreadyPeer, CFSTR("Cannot request admission when already a peer"), NULL, error));
+    
+    CFIndex total = CFArrayRemoveAllWithMatchingID(circle->applicants, SOSFullPeerInfoGetPeerInfo(requestor));
+    
+    (void) total; // Suppress unused warning in release code.
+    assert(total <= 1); // We should at most be in the list once.
+
+    total = CFArrayRemoveAllWithMatchingID(circle->rejected_applicants, SOSFullPeerInfoGetPeerInfo(requestor));
+    
+    (void) total; // Suppress unused warning in release code.
+    assert(total <= 1); // We should at most be in the list once.
+   
+    
+    // Refetch the current PeerInfo as the promtion above can change it.
+    CFArrayAppendValue(circle->applicants, SOSFullPeerInfoGetPeerInfo(requestor));
+    
+    return true;
+    
+fail:
+    return false;
+    
+}
+
+bool SOSCircleRequestReadmission(SOSCircleRef circle, SecKeyRef user_pubkey, SOSFullPeerInfoRef requestor, CFErrorRef *error) {
+    bool success = false;
+    
+    SOSPeerInfoRef peer = SOSFullPeerInfoGetPeerInfo(requestor);
+    require_quiet(SOSPeerInfoApplicationVerify(peer, user_pubkey, error), fail);
+    success = SOSCircleRecordAdmission(circle, user_pubkey, requestor, error);
+fail:
+    return success;
+}
+
+bool SOSCircleRequestAdmission(SOSCircleRef circle, SecKeyRef user_privkey, SOSFullPeerInfoRef requestor, CFErrorRef *error) {
+    bool success = false;
+    
+    SecKeyRef user_pubkey = SecKeyCreatePublicFromPrivate(user_privkey);
+    require_action_quiet(user_pubkey, fail, SOSCreateError(kSOSErrorBadKey, CFSTR("No public key for key"), NULL, error));
+
+    require(SOSFullPeerInfoPromoteToApplication(requestor, user_privkey, error), fail);
+    
+    success = SOSCircleRecordAdmission(circle, user_pubkey, requestor, error);
+fail:
+    CFReleaseNull(user_pubkey);
+    return success;
+}
+
+
+bool SOSCircleUpdatePeerInfo(SOSCircleRef circle, SOSPeerInfoRef replacement_peer_info) {
+    __block bool replaced = false;
+    CFStringRef replacement_peer_id = SOSPeerInfoGetPeerID(replacement_peer_info);
+    
+    CFMutableArrayModifyValues(circle->peers, ^const void *(const void *value) {
+        if (CFEqual(replacement_peer_id, SOSPeerInfoGetPeerID((SOSPeerInfoRef) value))
+         && !CFEqual(replacement_peer_info, value)) {
+            replaced = true;
+            return replacement_peer_info;
+        }
+      
+        return value;
+    });
+    return replaced;
+}
+
+bool SOSCircleRemovePeer(SOSCircleRef circle, SecKeyRef user_privkey, SOSFullPeerInfoRef requestor, SOSPeerInfoRef peer_to_remove, CFErrorRef *error) {
+    SOSPeerInfoRef requestor_peer_info = SOSFullPeerInfoGetPeerInfo(requestor);
+        
+    if (SOSCircleHasApplicant(circle, peer_to_remove, error)) {
+        return SOSCircleRejectRequest(circle, requestor, peer_to_remove, error);
+    }
+
+    if (!SOSCircleHasPeer(circle, requestor_peer_info, error)) {
+        SOSCreateError(kSOSErrorAlreadyPeer, CFSTR("Must be peer to remove peer"), NULL, error);
+        return false;
+    }
+
+    CFArrayRemoveAllWithMatchingID(circle->peers, peer_to_remove);
+
+    SOSCircleGenerationSign(circle, user_privkey, requestor, error);
+
+    return true;
+}
+
+bool SOSCircleAcceptRequest(SOSCircleRef circle, SecKeyRef user_privkey, SOSFullPeerInfoRef device_approver, SOSPeerInfoRef peerInfo, CFErrorRef *error) {
+    SOSCircleAssertStable(circle);
+
+    CFIndex total = CFArrayRemoveAllWithMatchingID(circle->applicants, peerInfo);
+    SecKeyRef publicKey = NULL;
+    bool result = false;
+
+    require_action_quiet(total != 0, fail, 
+                         SOSCreateError(kSOSErrorNotApplicant, CFSTR("Cannot accept non-applicant"), NULL, error));
+    
+    publicKey = SecKeyCreatePublicFromPrivate(user_privkey);
+    require_quiet(SOSPeerInfoApplicationVerify(peerInfo, publicKey, error), fail);
+
+    assert(total == 1);
+    
+    CFArrayAppendValue(circle->peers, peerInfo);
+    result = SOSCircleGenerationSign(circle, user_privkey, device_approver, error);
+    secnotice("circle", "Accepted %@", peerInfo);
+
+fail:
+    CFReleaseNull(publicKey);
+    return result;
+}
+
+bool SOSCircleWithdrawRequest(SOSCircleRef circle, SOSPeerInfoRef peerInfo, CFErrorRef *error) {
+    SOSCircleAssertStable(circle);
+
+#ifndef NDEBUG
+    CFIndex total =
+#endif
+        CFArrayRemoveAllWithMatchingID(circle->applicants, peerInfo);
+
+    assert(total <= 1);
+    
+    return true;
+}
+
+bool SOSCircleRemoveRejectedPeer(SOSCircleRef circle, SOSPeerInfoRef peerInfo, CFErrorRef *error) {
+    SOSCircleAssertStable(circle);
+    
+#ifndef NDEBUG
+    CFIndex total =
+#endif
+    CFArrayRemoveAllWithMatchingID(circle->rejected_applicants, peerInfo);
+    
+    assert(total <= 1);
+    
+    return true;
+}
+
+
+bool SOSCircleRejectRequest(SOSCircleRef circle, SOSFullPeerInfoRef device_rejector,
+                            SOSPeerInfoRef peerInfo, CFErrorRef *error) {
+    SOSCircleAssertStable(circle);
+
+    if (CFEqual(SOSPeerInfoGetPeerID(peerInfo), SOSPeerInfoGetPeerID(SOSFullPeerInfoGetPeerInfo(device_rejector))))
+        return SOSCircleWithdrawRequest(circle, peerInfo, error);
+
+	CFIndex total = CFArrayRemoveAllWithMatchingID(circle->applicants, peerInfo);
+    
+    if (total == 0) {
+        SOSCreateError(kSOSErrorNotApplicant, CFSTR("Cannot reject non-applicant"), NULL, error);
+        return false;
+    }
+    assert(total == 1);
+    
+    CFArrayAppendValue(circle->rejected_applicants, peerInfo);
+    
+    // TODO: Maybe we sign the rejection with device_rejector.
+    
+    return true;
+}
+
+bool SOSCircleAcceptRequests(SOSCircleRef circle, SecKeyRef user_privkey, SOSFullPeerInfoRef device_approver,
+                             CFErrorRef *error) {
+    // Returns true if we accepted someone and therefore have to post the circle back to KVS
+    __block bool result = false;
+    
+    SOSCircleForEachApplicant(circle, ^(SOSPeerInfoRef peer) {
+        if (!SOSCircleAcceptRequest(circle, user_privkey, device_approver, peer, error))
+            printf("error in SOSCircleAcceptRequest\n");
+        else {
+            secnotice("circle", "Accepted peer: %@", peer);
+            result = true;
+        }
+    });
+    
+    if (result) {
+        SOSCircleGenerationSign(circle, user_privkey, device_approver, error);
+        secnotice("circle", "Countersigned accepted requests");
+    }
+
+    return result;
+}
+
+bool SOSCirclePeerSigUpdate(SOSCircleRef circle, SecKeyRef userPrivKey, SOSFullPeerInfoRef fpi,
+                             CFErrorRef *error) {
+    // Returns true if we accepted someone and therefore have to post the circle back to KVS
+    __block bool result = false;
+    SecKeyRef userPubKey = SecKeyCreatePublicFromPrivate(userPrivKey);
+
+    // We're going to remove any applicants using a mismatched user key.
+    SOSCircleForEachApplicant(circle, ^(SOSPeerInfoRef peer) {
+        if(!SOSPeerInfoApplicationVerify(peer, userPubKey, NULL)) {
+            if(!SOSCircleRejectRequest(circle, fpi, peer, NULL)) {
+                // do we care?
+            }
+        }
+    });
+    
+    result = SOSCircleUpdatePeerInfo(circle, SOSFullPeerInfoGetPeerInfo(fpi));
+    
+    if (result) {
+        SOSCircleGenerationSign(circle, userPrivKey, fpi, error);
+        secnotice("circle", "Generation signed updated signatures on peerinfo");
+    }
+    
+    return result;
+}
+
+SOSPeerInfoRef SOSCircleCopyPeerInfo(SOSCircleRef circle, CFStringRef peer_id, CFErrorRef *error) {
+    __block SOSPeerInfoRef result = NULL;
+
+    CFArrayForEach(circle->peers, ^(const void *value) {
+        if (result == NULL) {
+            SOSPeerInfoRef tpi = (SOSPeerInfoRef)value;
+            if (CFEqual(SOSPeerInfoGetPeerID(tpi), peer_id))
+                result = tpi;
+        }
+    });
+
+    CFRetainSafe(result);
+    return result;
+}
+
+
+static inline void SOSCircleForEachPeerMatching(SOSCircleRef circle,
+                                                void (^action)(SOSPeerInfoRef peer),
+                                                bool (^condition)(SOSPeerInfoRef peer)) {
+    CFArrayForEach(circle->peers, ^(const void *value) {
+        SOSPeerInfoRef peer = (SOSPeerInfoRef) value;
+        if (condition(peer))
+            action(peer);
+    });
+}
+
+void SOSCircleForEachPeer(SOSCircleRef circle, void (^action)(SOSPeerInfoRef peer)) {
+    SOSCircleForEachPeerMatching(circle, action, ^bool(SOSPeerInfoRef peer) {
+        return !SOSPeerInfoIsRetirementTicket(peer) && !SOSPeerInfoIsCloudIdentity(peer);
+    });
+}
+
+void SOSCircleForEachRetiredPeer(SOSCircleRef circle, void (^action)(SOSPeerInfoRef peer)) {
+    SOSCircleForEachPeerMatching(circle, action, ^bool(SOSPeerInfoRef peer) {
+        return SOSPeerInfoIsRetirementTicket(peer);
+    });
+}
+
+void SOSCircleForEachActivePeer(SOSCircleRef circle, void (^action)(SOSPeerInfoRef peer)) {
+    SOSCircleForEachPeerMatching(circle, action, ^bool(SOSPeerInfoRef peer) {
+        return true;
+    });
+}
+
+void SOSCircleForEachActiveValidPeer(SOSCircleRef circle, SecKeyRef user_public_key, void (^action)(SOSPeerInfoRef peer)) {
+    SOSCircleForEachPeerMatching(circle, action, ^bool(SOSPeerInfoRef peer) {
+        return SOSPeerInfoApplicationVerify(peer, user_public_key, NULL);
+    });
+}
+
+void SOSCircleForEachApplicant(SOSCircleRef circle, void (^action)(SOSPeerInfoRef peer)) {
+    CFArrayForEach(circle->applicants, ^(const void*value) { action((SOSPeerInfoRef) value); } );
+}
+
+
+CFMutableArrayRef SOSCircleCopyPeers(SOSCircleRef circle, CFAllocatorRef allocator) {
+    SOSCircleAssertStable(circle);
+    
+    CFMutableArrayRef result = CFArrayCreateMutableForCFTypes(allocator);
+    
+    SOSCircleForEachPeer(circle, ^(SOSPeerInfoRef peer) {
+        CFArrayAppendValue(result, peer);
+    });
+    
+    return result;
+}
+
+CFMutableArrayRef SOSCircleCopyConcurringPeers(SOSCircleRef circle, CFErrorRef* error) {
+    SOSCircleAssertStable(circle);
+
+    CFMutableArrayRef concurringPeers = CFArrayCreateMutableForCFTypes(kCFAllocatorDefault);
+    
+    SOSCircleForEachActivePeer(circle, ^(SOSPeerInfoRef peer) {
+        CFErrorRef error = NULL;
+        if (SOSCircleVerifyPeerSigned(circle, peer, &error)) {
+            CFArrayAppendValue(concurringPeers, peer);
+        } else if (error != NULL) {
+            secerror("Error checking concurrence: %@", error);
+        }
+        CFReleaseNull(error);
+    });
+
+    return concurringPeers;
+}
+
+
+//
+// Stuff above this line is really SOSCircleInfo below the line is the active SOSCircle functionality
+//
+
+static SOSPeerRef SOSCircleCopyPeer(SOSCircleRef circle, SOSFullPeerInfoRef myRef, SOSPeerSendBlock sendBlock,
+                                    CFStringRef peer_id, CFErrorRef *error) {
+    SOSPeerRef peer = NULL;
+    SOSPeerInfoRef peer_info = SOSCircleCopyPeerInfo(circle, peer_id, error);
+    //TODO: if (peer is legit member of us then good otherwise bail) {
+    //}
+    if (peer_info) {
+        peer = SOSPeerCreate(myRef, peer_info, error, sendBlock);
+        CFReleaseNull(peer_info);
+    }
+    return peer;
+}
+
+
+static bool SOSCircleDoWithPeer(SOSFullPeerInfoRef myRef, SOSCircleRef circle, SOSDataSourceFactoryRef factory,
+                                SOSPeerSendBlock sendBlock, CFStringRef peer_id, bool readOnly,
+                                CFErrorRef* error, bool (^do_action)(SOSEngineRef engine, SOSPeerRef peer, CFErrorRef *error))
+{
+    bool success = false;
+    SOSEngineRef engine = NULL;
+    SOSPeerRef peer = NULL;
+    SOSDataSourceRef ds = NULL;
+
+    peer = SOSCircleCopyPeer(circle, myRef, sendBlock, peer_id, error);
+    require(peer, exit);
+
+    ds = factory->create_datasource(factory, SOSCircleGetName(circle), readOnly, error);
+    require(ds, exit);
+
+    engine = SOSEngineCreate(ds, error); // Hand off DS to engine.
+    ds = NULL;
+    require(engine, exit);
+
+    success = do_action(engine, peer, error);
+
+exit:
+    if (ds)
+        ds->release(ds);
+    if (engine)
+        SOSEngineDispose(engine);
+    if (peer)
+        SOSPeerDispose(peer);
+
+    return success;
+}
+
+bool SOSCircleSyncWithPeer(SOSFullPeerInfoRef myRef, SOSCircleRef circle, SOSDataSourceFactoryRef factory,
+                           SOSPeerSendBlock sendBlock, CFStringRef peer_id,
+                           CFErrorRef *error)
+{
+    return SOSCircleDoWithPeer(myRef, circle, factory, sendBlock, peer_id, true, error, ^bool(SOSEngineRef engine, SOSPeerRef peer, CFErrorRef *error) {
+        return SOSPeerStartSync(peer, engine, error) != kSOSPeerCoderFailure;
+    });
+}
+
+bool SOSCircleHandlePeerMessage(SOSCircleRef circle, SOSFullPeerInfoRef myRef, SOSDataSourceFactoryRef factory,
+                                SOSPeerSendBlock sendBlock, CFStringRef peer_id,
+                                CFDataRef message, CFErrorRef *error) {
+    return SOSCircleDoWithPeer(myRef, circle, factory, sendBlock, peer_id, false, error, ^bool(SOSEngineRef engine, SOSPeerRef peer, CFErrorRef *error) {
+        return SOSPeerHandleMessage(peer, engine, message, error) != kSOSPeerCoderFailure;
+    });
+}
+
+
+SOSFullPeerInfoRef SOSCircleGetiCloudFullPeerInfoRef(SOSCircleRef circle) {
+    __block SOSFullPeerInfoRef cloud_full_peer = NULL;
+    SOSCircleForEachActivePeer(circle, ^(SOSPeerInfoRef peer) {
+        if (SOSPeerInfoIsCloudIdentity(peer)) {
+            if (cloud_full_peer == NULL) {
+                CFErrorRef localError = NULL;
+                cloud_full_peer = SOSFullPeerInfoCreateCloudIdentity(kCFAllocatorDefault, peer, &localError);
+                
+                if (localError) {
+                    secerror("Found cloud peer in circle but can't make full peer: %@", localError);
+                    CFReleaseNull(localError);
+                }
+                
+            } else {
+                secerror("More than one cloud identity found in circle: %@", circle);
+            }
+        }
+    });
+    return cloud_full_peer;
+}
+
+
+