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ext4crypt: support synthetic keys v3 on May update

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Re-implemented SP800Derive in C++, which is added as the new key
derivation function in Android 9.0 May update. From file
services/core/java/com/android/server/locksettings/SP800Derive.java in
frameworks/base.

This is required to get TWRP working on any Android device that has a
screen lock set up after the May update.

Change-Id: I5c1a51b110033f2b0b75d5e36fd8098c05e95179
This commit is contained in:
Peter Cai
2019-05-24 20:41:12 +08:00
parent f5955b1cb4
commit ea1764c9fa
3 changed files with 55 additions and 13 deletions
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crypto/ext4crypt/HashPassword.cpp
+33
View File
@@ -27,11 +27,13 @@
#include <string>
#include <stdlib.h>
#include <openssl/sha.h>
#include <openssl/hmac.h>
#include "HashPassword.h"
#define PASS_PADDING_SIZE 128
#define SHA512_HEX_SIZE SHA512_DIGEST_LENGTH * 2
#define SHA256_HEX_SIZE SHA256_DIGEST_LENGTH * 2
void* PersonalizedHashBinary(const char* prefix, const char* key, const size_t key_size) {
size_t size = PASS_PADDING_SIZE + key_size;
@@ -78,6 +80,37 @@ std::string PersonalizedHash(const char* prefix, const std::string& Password) {
return PersonalizedHash(prefix, Password.c_str(), Password.size());
}
std::string PersonalizedHashSP800(const char* label, const char* context, const char* key, const size_t key_size) {
HMAC_CTX ctx;
HMAC_CTX_init(&ctx);
HMAC_Init_ex(&ctx, key, key_size, EVP_sha256(), NULL);
unsigned int counter = 1;
endianswap(&counter);
HMAC_Update(&ctx, (const unsigned char*)&counter, 4);
HMAC_Update(&ctx, (const unsigned char*)label, strlen(label));
const unsigned char divider = 0;
HMAC_Update(&ctx, &divider, 1);
HMAC_Update(&ctx, (const unsigned char*)context, strlen(context));
unsigned int contextDisambiguation = strlen(context) * 8;
endianswap(&contextDisambiguation);
HMAC_Update(&ctx, (const unsigned char*)&contextDisambiguation, 4);
unsigned int finalValue = 256;
endianswap(&finalValue);
HMAC_Update(&ctx, (const unsigned char*)&finalValue, 4);
unsigned char output[SHA256_DIGEST_LENGTH];
unsigned int out_size = 0;
HMAC_Final(&ctx, output, &out_size);
int index = 0;
char hex_hash[SHA256_HEX_SIZE + 1];
for(index = 0; index < SHA256_DIGEST_LENGTH; index++)
sprintf(hex_hash + (index * 2), "%02x", output[index]);
hex_hash[SHA256_HEX_SIZE] = 0;
std::string ret = hex_hash;
return ret;
}
std::string HashPassword(const std::string& Password) {
const char* prefix = FBE_PERSONALIZATION;
return PersonalizedHash(prefix, Password);