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verifier: update to support certificates using SHA-256

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(cherry picked from commit bac7fba027)

Change-Id: I01c38d7fea088622a8b0bbf2c833fa2d969417af
This commit is contained in:
Doug Zongker
2013-04-10 11:32:17 -07:00
committed by Kenny Root
parent 5c4e1dac0b
commit 30362a6ad1
13 changed files with 254 additions and 109 deletions
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verifier.cpp
+63 -17
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@@ -20,6 +20,7 @@
#include "mincrypt/rsa.h"
#include "mincrypt/sha.h"
#include "mincrypt/sha256.h"
#include <string.h>
#include <stdio.h>
@@ -34,7 +35,7 @@ extern RecoveryUI* ui;
// Return VERIFY_SUCCESS, VERIFY_FAILURE (if any error is encountered
// or no key matches the signature).
int verify_file(const char* path, const RSAPublicKey *pKeys, unsigned int numKeys) {
int verify_file(const char* path, const Certificate* pKeys, unsigned int numKeys) {
ui->SetProgress(0.0);
FILE* f = fopen(path, "rb");
@@ -68,6 +69,7 @@ int verify_file(const char* path, const RSAPublicKey *pKeys, unsigned int numKey
}
if (footer[2] != 0xff || footer[3] != 0xff) {
LOGE("footer is wrong\n");
fclose(f);
return VERIFY_FAILURE;
}
@@ -139,8 +141,19 @@ int verify_file(const char* path, const RSAPublicKey *pKeys, unsigned int numKey
#define BUFFER_SIZE 4096
SHA_CTX ctx;
SHA_init(&ctx);
bool need_sha1 = false;
bool need_sha256 = false;
for (i = 0; i < numKeys; ++i) {
switch (pKeys[i].hash_len) {
case SHA_DIGEST_SIZE: need_sha1 = true; break;
case SHA256_DIGEST_SIZE: need_sha256 = true; break;
}
}
SHA_CTX sha1_ctx;
SHA256_CTX sha256_ctx;
SHA_init(&sha1_ctx);
SHA256_init(&sha256_ctx);
unsigned char* buffer = (unsigned char*)malloc(BUFFER_SIZE);
if (buffer == NULL) {
LOGE("failed to alloc memory for sha1 buffer\n");
@@ -159,7 +172,8 @@ int verify_file(const char* path, const RSAPublicKey *pKeys, unsigned int numKey
fclose(f);
return VERIFY_FAILURE;
}
SHA_update(&ctx, buffer, size);
if (need_sha1) SHA_update(&sha1_ctx, buffer, size);
if (need_sha256) SHA256_update(&sha256_ctx, buffer, size);
so_far += size;
double f = so_far / (double)signed_len;
if (f > frac + 0.02 || size == so_far) {
@@ -170,12 +184,21 @@ int verify_file(const char* path, const RSAPublicKey *pKeys, unsigned int numKey
fclose(f);
free(buffer);
const uint8_t* sha1 = SHA_final(&ctx);
const uint8_t* sha1 = SHA_final(&sha1_ctx);
const uint8_t* sha256 = SHA256_final(&sha256_ctx);
for (i = 0; i < numKeys; ++i) {
const uint8_t* hash;
switch (pKeys[i].hash_len) {
case SHA_DIGEST_SIZE: hash = sha1; break;
case SHA256_DIGEST_SIZE: hash = sha256; break;
default: continue;
}
// The 6 bytes is the "(signature_start) $ff $ff (comment_size)" that
// the signing tool appends after the signature itself.
if (RSA_verify(pKeys+i, eocd + eocd_size - 6 - RSANUMBYTES,
RSANUMBYTES, sha1)) {
if (RSA_verify(pKeys[i].public_key, eocd + eocd_size - 6 - RSANUMBYTES,
RSANUMBYTES, hash, pKeys[i].hash_len)) {
LOGI("whole-file signature verified against key %d\n", i);
free(eocd);
return VERIFY_SUCCESS;
@@ -207,10 +230,19 @@ int verify_file(const char* path, const RSAPublicKey *pKeys, unsigned int numKey
// The file may contain multiple keys in this format, separated by
// commas. The last key must not be followed by a comma.
//
// A Certificate is a pair of an RSAPublicKey and a particular hash
// (we support SHA-1 and SHA-256; we store the hash length to signify
// which is being used). The hash used is implied by the version number.
//
// 1: 2048-bit RSA key with e=3 and SHA-1 hash
// 2: 2048-bit RSA key with e=65537 and SHA-1 hash
// 3: 2048-bit RSA key with e=3 and SHA-256 hash
// 4: 2048-bit RSA key with e=65537 and SHA-256 hash
//
// Returns NULL if the file failed to parse, or if it contain zero keys.
RSAPublicKey*
Certificate*
load_keys(const char* filename, int* numKeys) {
RSAPublicKey* out = NULL;
Certificate* out = NULL;
*numKeys = 0;
FILE* f = fopen(filename, "r");
@@ -224,24 +256,38 @@ load_keys(const char* filename, int* numKeys) {
bool done = false;
while (!done) {
++*numKeys;
out = (RSAPublicKey*)realloc(out, *numKeys * sizeof(RSAPublicKey));
RSAPublicKey* key = out + (*numKeys - 1);
out = (Certificate*)realloc(out, *numKeys * sizeof(Certificate));
Certificate* cert = out + (*numKeys - 1);
cert->public_key = (RSAPublicKey*)malloc(sizeof(RSAPublicKey));
char start_char;
if (fscanf(f, " %c", &start_char) != 1) goto exit;
if (start_char == '{') {
// a version 1 key has no version specifier.
key->exponent = 3;
cert->public_key->exponent = 3;
cert->hash_len = SHA_DIGEST_SIZE;
} else if (start_char == 'v') {
int version;
if (fscanf(f, "%d {", &version) != 1) goto exit;
if (version == 2) {
key->exponent = 65537;
} else {
goto exit;
switch (version) {
case 2:
cert->public_key->exponent = 65537;
cert->hash_len = SHA_DIGEST_SIZE;
break;
case 3:
cert->public_key->exponent = 3;
cert->hash_len = SHA256_DIGEST_SIZE;
break;
case 4:
cert->public_key->exponent = 65537;
cert->hash_len = SHA256_DIGEST_SIZE;
break;
default:
goto exit;
}
}
RSAPublicKey* key = cert->public_key;
if (fscanf(f, " %i , 0x%x , { %u",
&(key->len), &(key->n0inv), &(key->n[0])) != 3) {
goto exit;
@@ -274,7 +320,7 @@ load_keys(const char* filename, int* numKeys) {
goto exit;
}
LOGI("read key e=%d\n", key->exponent);
LOGI("read key e=%d hash=%d\n", key->exponent, cert->hash_len);
}
}