diff options
Diffstat (limited to 'twmincrypt/twrsa.c')
| -rw-r--r-- | twmincrypt/twrsa.c | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/twmincrypt/twrsa.c b/twmincrypt/twrsa.c new file mode 100644 index 000000000..52d6bfbc2 --- /dev/null +++ b/twmincrypt/twrsa.c @@ -0,0 +1,199 @@ +/* rsa.c +** +** Copyright 2008, The Android Open Source Project +** +** Redistribution and use in source and binary forms, with or without +** modification, are permitted provided that the following conditions are met: +** * Redistributions of source code must retain the above copyright +** notice, this list of conditions and the following disclaimer. +** * Redistributions in binary form must reproduce the above copyright +** notice, this list of conditions and the following disclaimer in the +** documentation and/or other materials provided with the distribution. +** * Neither the name of Google Inc. nor the names of its contributors may +** be used to endorse or promote products derived from this software +** without specific prior written permission. +** +** THIS SOFTWARE IS PROVIDED BY Google Inc. ``AS IS'' AND ANY EXPRESS OR +** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF +** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO +** EVENT SHALL Google Inc. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, +** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; +** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, +** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR +** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF +** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +*/ + +#include "twrsa.h" +#include "twsha.h" +#include "common.h" + +/* a[] -= mod */ +static void subM(const 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(const 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(const 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(const 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 modpow3(const RSAPublicKey *key, + uint8_t* inout) { + uint32_t a[RSANUMWORDS]; + uint32_t aR[RSANUMWORDS]; + uint32_t aaR[RSANUMWORDS]; + uint32_t *aaa = aR; /* 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 */ + montMul(key, aaR, aR, aR); /* aaR = aR * aR / R mod M */ + montMul(key, aaa, aaR, a); /* aaa = aaR * 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 - SHA_DIGEST_SIZE] = { + 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 +}; + +/* Verify a 2048 bit RSA PKCS1.5 signature against an expected SHA-1 hash. +** Returns 0 on failure, 1 on success. +*/ +int RSA_verify(const 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) { + buf[i] = signature[i]; + } + + modpow3(key, buf); + + /* Check pkcs1.5 padding bytes. */ + for (i = 0; i < (int) sizeof(padding); ++i) { + if (buf[i] != padding[i]) { + return 0; + } + } + + /* Check sha digest matches. */ + for (; i < len; ++i) { + if (buf[i] != *sha++) { + return 0; + } + } + + return 1; +} |