diff options
Diffstat (limited to 'libc/rsa.c')
-rw-r--r-- | libc/rsa.c | 168 |
1 files changed, 0 insertions, 168 deletions
diff --git a/libc/rsa.c b/libc/rsa.c deleted file mode 100644 index 9c5636b..0000000 --- a/libc/rsa.c +++ /dev/null @@ -1,168 +0,0 @@ -// Copyright 2008-2010 Google Inc. All Rights Reserved. -// Author: mschilder@google.com (Marius Schilder) - -#include "rsa.h" -#include "sha.h" - -// a[] -= mod -static void subM(RSAPublicKey key, - uint32_t* a) { - int64_t A = 0; - int i; - for (i = 0; i < key->len; ++i) { - A += (uint64_t)a[i] - key->n[i]; - a[i] = (uint32_t)A; - A >>= 32; - } -} - -// return a[] >= mod -static int geM(RSAPublicKey key, - const uint32_t* a) { - int i; - for (i = key->len; i;) { - --i; - if (a[i] < key->n[i]) return 0; - if (a[i] > key->n[i]) return 1; - } - return 1; // equal -} - -// montgomery c[] += a * b[] / R % mod -static void montMulAdd(RSAPublicKey key, - uint32_t* c, - const uint32_t a, - const uint32_t* b) { - uint64_t A = (uint64_t)a * b[0] + c[0]; - uint32_t d0 = (uint32_t)A * key->n0inv; - uint64_t B = (uint64_t)d0 * key->n[0] + (uint32_t)A; - int i; - - for (i = 1; i < key->len; ++i) { - A = (A >> 32) + (uint64_t)a * b[i] + c[i]; - B = (B >> 32) + (uint64_t)d0 * key->n[i] + (uint32_t)A; - c[i - 1] = (uint32_t)B; - } - - A = (A >> 32) + (B >> 32); - - c[i - 1] = (uint32_t)A; - - if (A >> 32) { - subM(key, c); - } -} - -// montgomery c[] = a[] * b[] / R % mod -static void montMul(RSAPublicKey key, - uint32_t* c, - const uint32_t* a, - const uint32_t* b) { - int i; - for (i = 0; i < key->len; ++i) { - c[i] = 0; - } - for (i = 0; i < key->len; ++i) { - montMulAdd(key, c, a[i], b); - } -} - -// In-place public exponentiation. -// Input and output big-endian byte array in inout. -static void modpowF4(RSAPublicKey key, - uint8_t* inout) { - uint32_t a[RSANUMWORDS]; - uint32_t aR[RSANUMWORDS]; - uint32_t aaR[RSANUMWORDS]; - uint32_t* aaa = aaR; // Re-use location. - int i; - - // Convert from big endian byte array to little endian word array. - for (i = 0; i < key->len; ++i) { - uint32_t tmp = - (inout[((key->len - 1 - i) * 4) + 0] << 24) | - (inout[((key->len - 1 - i) * 4) + 1] << 16) | - (inout[((key->len - 1 - i) * 4) + 2] << 8) | - (inout[((key->len - 1 - i) * 4) + 3] << 0); - a[i] = tmp; - } - - montMul(key, aR, a, key->rr); // aR = a * RR / R mod M - for (i = 0; i < 16; i += 2) { - montMul(key, aaR, aR, aR); // aaR = aR * aR / R mod M - montMul(key, aR, aaR, aaR); // aR = aaR * aaR / R mod M - } - montMul(key, aaa, aR, a); // aaa = aR * a / R mod M - - // Make sure aaa < mod; aaa is at most 1x mod too large. - if (geM(key, aaa)) { - subM(key, aaa); - } - - // Convert to bigendian byte array - for (i = key->len - 1; i >= 0; --i) { - uint32_t tmp = aaa[i]; - *inout++ = tmp >> 24; - *inout++ = tmp >> 16; - *inout++ = tmp >> 8; - *inout++ = tmp >> 0; - } -} - -// Expected PKCS1.5 signature padding bytes, for a keytool RSA signature. -// Has the 0-length optional parameter encoded in the ASN1 (as opposed to the -// other flavor which omits the optional parameter entirely). This code does not -// accept signatures without the optional parameter. -/* -static const uint8_t padding[RSANUMBYTES] = { -0x00,0x01,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0x00,0x30,0x21,0x30,0x09,0x06,0x05,0x2b,0x0e,0x03,0x02,0x1a,0x05,0x00,0x04,0x14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 -}; -*/ - -// SHA-1 of PKCS1.5 signature padding for 2048 bit, as above. -// At the location of the bytes of the hash all 00 are hashed. -static const uint8_t kExpectedPadShaRsa2048[SHA_DIGEST_SIZE] = { - 0xdc, 0xbd, 0xbe, 0x42, 0xd5, 0xf5, 0xa7, 0x2e, 0x6e, 0xfc, - 0xf5, 0x5d, 0xaf, 0x9d, 0xea, 0x68, 0x7c, 0xfb, 0xf1, 0x67 -}; - -// Verify a 2048 bit RSA PKCS1.5 signature against an expected SHA-1 hash. -// Returns 0 on failure, 1 on success. -int RSA_verify(RSAPublicKey key, - const uint8_t* signature, - const int len, - const uint8_t* sha) { - uint8_t buf[RSANUMBYTES]; - int i; - - if (key->len != RSANUMWORDS) { - return 0; // Wrong key passed in. - } - - if (len != sizeof(buf)) { - return 0; // Wrong input length. - } - - for (i = 0; i < len; ++i) { // Copy input to local workspace. - buf[i] = signature[i]; - } - - modpowF4(key, buf); // In-place exponentiation. - - // Xor sha portion, so it all becomes 00 iff equal. - for (i = len - SHA_DIGEST_SIZE; i < len; ++i) { - buf[i] ^= *sha++; - } - - // Hash resulting buf, in-place. - SHA(buf, len, buf); - - // Compare against expected hash value. - for (i = 0; i < SHA_DIGEST_SIZE; ++i) { - if (buf[i] != kExpectedPadShaRsa2048[i]) { - return 0; - } - } - - return 1; // All checked out OK. -} |