#include "SecOTRDHKey.h"
#include <utilities/SecCFWrappers.h>
#include "SecOTRMath.h"
#include "SecOTRPacketData.h"
#include <corecrypto/ccn.h>
#include <corecrypto/ccsha1.h>
#include <corecrypto/ccec_priv.h>
#include <corecrypto/ccec.h>
#include <CommonCrypto/CommonRandomSPI.h>
#ifdef USECOMMONCRYPTO
#include <CommonCrypto/CommonDigest.h>
#endif
#define kECKeySize 256
struct _SecOTRFullDHKey {
CFRuntimeBase _base;
ccec_full_ctx_decl(ccn_sizeof(kECKeySize), _key);
uint8_t keyHash[CCSHA1_OUTPUT_SIZE];
};
CFGiblisFor(SecOTRFullDHKey);
static size_t AppendECPublicKeyAsDATA(CFMutableDataRef data, ccec_pub_ctx_t public_key)
{
size_t size = ccec_export_pub_size(public_key);
AppendLong(data, (uint32_t)size);
ccec_export_pub(public_key, CFDataIncreaseLengthAndGetMutableBytes(data, (CFIndex)size));
return size;
}
static CF_RETURNS_RETAINED CFStringRef SecOTRFullDHKeyCopyDescription(CFTypeRef cf)
{
SecOTRFullDHKeyRef session = (SecOTRFullDHKeyRef)cf;
return CFStringCreateWithFormat(kCFAllocatorDefault,NULL,CFSTR("<SecOTRFullDHKeyRef: %p>"), session);
}
static void SecOTRFullDHKeyDestroy(CFTypeRef cf)
{
SecOTRFullDHKeyRef fullKey = (SecOTRFullDHKeyRef)cf;
bzero(fullKey->_key, sizeof(fullKey->_key));
}
SecOTRFullDHKeyRef SecOTRFullDHKCreate(CFAllocatorRef allocator)
{
SecOTRFullDHKeyRef newFDHK = CFTypeAllocate(SecOTRFullDHKey, struct _SecOTRFullDHKey, allocator);
SecFDHKNewKey(newFDHK);
return newFDHK;
}
SecOTRFullDHKeyRef SecOTRFullDHKCreateFromBytes(CFAllocatorRef allocator, const uint8_t**bytes, size_t*size)
{
SecOTRFullDHKeyRef newFDHK = CFTypeAllocate(SecOTRFullDHKey, struct _SecOTRFullDHKey, allocator);
ccec_ctx_init(ccec_cp_256(), newFDHK->_key);
uint32_t publicKeySize;
require_noerr(ReadLong(bytes, size, &publicKeySize), fail);
require(publicKeySize <= *size, fail);
require_noerr(ccec_import_pub(ccec_cp_256(), publicKeySize, *bytes, newFDHK->_key), fail);
ccdigest(ccsha1_di(), publicKeySize, *bytes, newFDHK->keyHash);
*size -= publicKeySize;
*bytes += publicKeySize;
require_noerr(ReadMPI(bytes, size, ccec_ctx_n(newFDHK->_key), ccec_ctx_k(newFDHK->_key)), fail);
return newFDHK;
fail:
CFReleaseNull(newFDHK);
return NULL;
}
void SecFDHKNewKey(SecOTRFullDHKeyRef fullKey)
{
struct ccrng_state *rng=ccDRBGGetRngState();
#if defined(CCECDH_AVAILABLE)
ccecdh_generate_key(ccec_cp_256(), rng, fullKey->_key);
#else
ccec_generate_key(ccec_cp_256(), rng, fullKey->_key);
#endif
size_t size = ccec_export_pub_size(fullKey->_key);
uint8_t publicKey[size];
ccec_export_pub(fullKey->_key, publicKey);
ccdigest(ccsha1_di(), size, publicKey, fullKey->keyHash);
}
void SecFDHKAppendSerialization(SecOTRFullDHKeyRef fullKey, CFMutableDataRef appendTo)
{
AppendECPublicKeyAsDATA(appendTo, fullKey->_key);
AppendMPI(appendTo, ccec_ctx_n(fullKey->_key), ccec_ctx_k(fullKey->_key));
}
void SecFDHKAppendPublicSerialization(SecOTRFullDHKeyRef fullKey, CFMutableDataRef appendTo)
{
if(ccec_ctx_bitlen(fullKey->_key) != kECKeySize) return;
AppendECPublicKeyAsDATA(appendTo, fullKey->_key);
}
uint8_t* SecFDHKGetHash(SecOTRFullDHKeyRef fullKey)
{
return fullKey->keyHash;
}
struct _SecOTRPublicDHKey {
CFRuntimeBase _base;
ccec_pub_ctx_decl(ccn_sizeof(kECKeySize), _key);
uint8_t keyHash[CCSHA1_OUTPUT_SIZE];
};
CFGiblisFor(SecOTRPublicDHKey);
static CF_RETURNS_RETAINED CFStringRef SecOTRPublicDHKeyCopyDescription(CFTypeRef cf) {
SecOTRPublicDHKeyRef session = (SecOTRPublicDHKeyRef)cf;
return CFStringCreateWithFormat(kCFAllocatorDefault,NULL,CFSTR("<SecOTRPublicDHKeyRef: %p>"), session);
}
static void SecOTRPublicDHKeyDestroy(CFTypeRef cf) {
SecOTRPublicDHKeyRef pubKey = (SecOTRPublicDHKeyRef)cf;
(void) pubKey;
}
static void ccec_copy_public(ccec_pub_ctx_t source, ccec_pub_ctx_t dest)
{
ccec_ctx_cp(dest) = ccec_ctx_cp(source);
ccn_set(3*ccec_ctx_n(source), (cc_unit*) ccec_ctx_point(dest)._p, (cc_unit*) ccec_ctx_point(source)._p);
}
SecOTRPublicDHKeyRef SecOTRPublicDHKCreateFromFullKey(CFAllocatorRef allocator, SecOTRFullDHKeyRef full)
{
SecOTRPublicDHKeyRef newPDHK = CFTypeAllocate(SecOTRPublicDHKey, struct _SecOTRPublicDHKey, allocator);
ccec_copy_public(full->_key, newPDHK->_key);
memcpy(newPDHK->keyHash, full->keyHash, CCSHA1_OUTPUT_SIZE);
return newPDHK;
}
SecOTRPublicDHKeyRef SecOTRPublicDHKCreateFromSerialization(CFAllocatorRef allocator, const uint8_t** bytes, size_t *size)
{
SecOTRPublicDHKeyRef newPDHK = CFTypeAllocate(SecOTRPublicDHKey, struct _SecOTRPublicDHKey, allocator);
uint32_t publicKeySize;
require_noerr(ReadLong(bytes, size, &publicKeySize), fail);
require(publicKeySize <= *size, fail);
require_noerr(ccec_import_pub(ccec_cp_256(), publicKeySize, *bytes, newPDHK->_key), fail);
ccdigest(ccsha1_di(), publicKeySize, *bytes, newPDHK->keyHash);
*size -= publicKeySize;
*bytes += publicKeySize;
return newPDHK;
fail:
CFReleaseNull(newPDHK);
return NULL;
}
SecOTRPublicDHKeyRef SecOTRPublicDHKCreateFromBytes(CFAllocatorRef allocator, const uint8_t** bytes, size_t *size)
{
SecOTRPublicDHKeyRef newPDHK = CFTypeAllocate(SecOTRPublicDHKey, struct _SecOTRPublicDHKey, allocator);
require_noerr(ccec_import_pub(ccec_cp_256(), *size, *bytes, newPDHK->_key), fail);
ccdigest(ccsha1_di(), *size, *bytes, newPDHK->keyHash);
return newPDHK;
fail:
CFReleaseNull(newPDHK);
return NULL;
}
void SecPDHKAppendSerialization(SecOTRPublicDHKeyRef pubKey, CFMutableDataRef appendTo)
{
AppendECPublicKeyAsDATA(appendTo, pubKey->_key);
}
uint8_t* SecPDHKGetHash(SecOTRPublicDHKeyRef pubKey)
{
return pubKey->keyHash;
}
void SecPDHKeyGenerateS(SecOTRFullDHKeyRef myKey, SecOTRPublicDHKeyRef theirKey, cc_unit* s)
{
ccn_zero(kExponentiationUnits, s);
size_t keyLen = ccn_sizeof_n(kExponentiationUnits);
ccec_compute_key(myKey->_key, theirKey->_key, &keyLen, (uint8_t*)s);
}
static int ccec_cmp(ccec_pub_ctx_t l, ccec_pub_ctx_t r)
{
size_t lsize = ccec_export_pub_size(l);
size_t rsize = ccec_export_pub_size(r);
int result = 0;
if (lsize == rsize) {
uint8_t lpub[lsize];
uint8_t rpub[rsize];
ccec_export_pub(l, lpub);
ccec_export_pub(r, rpub);
result = memcmp(lpub, rpub, lsize);
} else {
result = rsize < lsize ? -1 : 1;
}
return result;
}
bool SecDHKIsGreater(SecOTRFullDHKeyRef myKey, SecOTRPublicDHKeyRef theirKey)
{
return ccec_cmp(myKey->_key, theirKey->_key) > 0;
}
static void DeriveKeys(CFDataRef dataToHash,
uint8_t* messageKey,
uint8_t* macKey)
{
if (messageKey == NULL && macKey == NULL)
return;
uint8_t hashedSharedKey[CCSHA1_OUTPUT_SIZE];
#ifdef USECOMMONCRYPTO
(void) CCDigest(kCCDigestSHA1, CFDataGetBytePtr(dataToHash), (uint32_t)CFDataGetLength(dataToHash), hashedSharedKey);
#else
ccdigest(ccsha1_di(), CFDataGetLength(dataToHash), CFDataGetBytePtr(dataToHash), hashedSharedKey);
#endif
if (messageKey)
memcpy(messageKey, hashedSharedKey, kOTRMessageKeyBytes);
if (macKey) {
#ifdef USECOMMONCRYPTO
(void) CCDigest(kCCDigestSHA1, messageKey, kOTRMessageKeyBytes, macKey);
#else
ccdigest(ccsha1_di(), kOTRMessageKeyBytes, messageKey, macKey);
#endif
}
bzero(hashedSharedKey, sizeof(hashedSharedKey));
}
void SecOTRDHKGenerateOTRKeys(SecOTRFullDHKeyRef myKey, SecOTRPublicDHKeyRef theirKey,
uint8_t* sendMessageKey, uint8_t* sendMacKey,
uint8_t* receiveMessageKey, uint8_t* receiveMacKey)
{
CFMutableDataRef dataToHash = CFDataCreateMutable(kCFAllocatorDefault, 0);
{
cc_unit s[kExponentiationUnits];
SecPDHKeyGenerateS(myKey, theirKey, s);
AppendByte(dataToHash, SecDHKIsGreater(myKey, theirKey) ? 0x01 : 0x02);
AppendMPI(dataToHash, kExponentiationUnits, s);
ccn_zero(kExponentiationUnits, s);
}
DeriveKeys(dataToHash, receiveMessageKey, receiveMacKey);
uint8_t *messageTypeByte = CFDataGetMutableBytePtr(dataToHash);
*messageTypeByte ^= 0x03;
DeriveKeys(dataToHash, sendMessageKey, sendMacKey);
CFReleaseNull(dataToHash);
}