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Refactor DH crypto functions
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@relatko
relatko committed Oct 6, 2023
1 parent 5d55ca6 commit 873c61c
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Showing 8 changed files with 698 additions and 385 deletions.
2 changes: 1 addition & 1 deletion MakefileTest.mk
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Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,7 @@ endef
.PHONY: speculos_port_5001_test_internal
speculos_port_5001_test_internal:
$(call run_announce,$@)
# $(call run_nodejs_test,5001,40001,getVersion.js)
$(call run_nodejs_test,5001,40001,getVersion.js)
$(call run_nodejs_test,5001,40001,getSerial.js)
$(call run_nodejs_test,5001,40001,getPublicKey.js)
$(call run_nodejs_test,5001,40001,decodeMessage.js)
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5 changes: 4 additions & 1 deletion src/decodeDH.c
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Expand Up @@ -503,7 +503,10 @@ void decode_handleAPDU(uint8_t p1,
TRACE("Decoding DH");
ASSERT(ctx->bufferLen <= SIZEOF(ctx->buffer));
TRACE_BUFFER(ctx->buffer, ctx->bufferLen);
ctx->bufferLen = dh_decode(&ctx->pathSpec, &ctx->otherPubKey, ctx->buffer, ctx->bufferLen);
uint16_t err = dh_decode(&ctx->pathSpec, &ctx->otherPubKey, ctx->buffer, &ctx->bufferLen);
if (err != SUCCESS) {
THROW(err);
}
ctx->messageDecodedMagic = DECODING_FINISHED_MAGIC;
ctx->bufferSentLen = 0;
TRACE_BUFFER(ctx->buffer, ctx->bufferLen);
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591 changes: 386 additions & 205 deletions src/diffieHellman.c
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185 changes: 134 additions & 51 deletions src/diffieHellman.h
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Expand Up @@ -39,63 +39,146 @@ typedef struct {

// Aes key is secret shared between us and the second party
typedef struct {
uint16_t initialized_magic;
cx_aes_key_t aesKey;
uint8_t km[DH_KM_SIZE];
} dh_aes_key_t;

// You may need to call multiple times if encryption spans multiple APDU's
// You may want to do something like
// APDU1 - dh_init_aes_key, dh_encode_init, dh_encode_append
// APDU2 - dh_init_aes_key, dh_encode_append
// APDU3 - dh_init_aes_key, dh_encode_append, dh_encode_finalize
// Do not forget to guarantee that dh_aes_key_t is zeroes at all times

__noinline_due_to_stack__ void dh_init_aes_key(dh_aes_key_t* dhKey,
const bip44_path_t* pathSpec,
const public_key_t* publicKey);

// Output data are base64 encrypted
__noinline_due_to_stack__ size_t dh_encode_init(dh_context_t* ctx,
const dh_aes_key_t* aes_key,
const uint8_t* iv,
size_t ivSize,
uint8_t* outBuffer,
size_t outSize);

// Output data are base64 encrypted
__noinline_due_to_stack__ size_t dh_encode_append(dh_context_t* ctx,
const dh_aes_key_t* aes_key,
const uint8_t* inBuffer,
size_t inSize,
uint8_t* outBuffer,
size_t outSize);

// Output data are base64 encrypted
__noinline_due_to_stack__ size_t dh_encode_finalize(dh_context_t* ctx,
const dh_aes_key_t* aes_key,
uint8_t* outBuffer,
size_t outSize);

// Convenience function to make all in one step
// Output data are base64 encrypted
__noinline_due_to_stack__ size_t dh_encode(bip44_path_t* pathSpec,
public_key_t* publicKey,
const uint8_t* iv,
size_t ivSize,
const uint8_t* inBuffer,
size_t inSize,
uint8_t* outBuffer,
size_t outSize);

// Inplace decoding function.
// Input data is NOT base64 encrypted
__noinline_due_to_stack__ size_t dh_decode(bip44_path_t* pathSpec,
public_key_t* publicKey,
uint8_t* buffer,
size_t inSize);
/**
* @brief Generates shared secret AES key. Use only in crypto functions to guarantee cleanup.
*
* @param[out] dhKey Resulting AES key.
*
* @param[in] pathSpec Our derivation path.
*
* @param[in] publicKey Their public key.
*
* @return Error code:
* - SUCCESS on success
* - ERR_REJECTED_BY_POLICY
* - ERR_ASSERT for other unexpected errors
*/
__noinline_due_to_stack__ WARN_UNUSED_RESULT uint16_t
dh_init_aes_key(dh_aes_key_t *dhKey, const bip44_path_t *pathSpec, const public_key_t *publicKey);

/**
* @brief Initiates DH+Base64 ecoding.
*
* @param[out] ctx DH encoding context.
*
* @param[in] pathSpec Our derivation path.
*
* @param[in] publicKey Their public key.
*
* @param[in] iv Initiatlization vector.
*
* @param[in] ivSize Size of initialization vector.
*
* @param[out] outBuffer Output buffer, initialization produces cyphertext.
*
* @param[in, out] outSize Size of output buffer. returns the number of new bytes.
*
* @return Error code:
* - SUCCESS on success
* - ERR_REJECTED_BY_POLICY
* - ERR_ASSERT for other unexpected errors
*/
__noinline_due_to_stack__ WARN_UNUSED_RESULT uint16_t dh_encode_init(dh_context_t *ctx,
const bip44_path_t *pathSpec,
const public_key_t *publicKey,
const uint8_t *iv,
uint16_t ivSize,
uint8_t *outBuffer,
uint16_t *outSize);

/**
* @brief Append to DH+Base64 ecoded data.
*
* @param[in, out] ctx DH encoding context.
*
* @param[in] pathSpec Our derivation path.
*
* @param[in] publicKey Their public key.
*
* @param[in] inBuffer Input buffer.
*
* @param[in] inSize Input buffer size.
*
* @param[out] outBuffer Output buffer, initialization produces cyphertext.
*
* @param[in, out] outSize Size of output buffer. returns the number of new bytes.
*
* @return Error code:
* - SUCCESS on success
* - ERR_REJECTED_BY_POLICY
* - ERR_ASSERT for other unexpected errors
*/
__noinline_due_to_stack__ WARN_UNUSED_RESULT uint16_t
dh_encode_append(dh_context_t *ctx,
const bip44_path_t *pathSpec,
const public_key_t *publicKey,
const uint8_t *inBuffer,
uint16_t inSize,
uint8_t *outBuffer,
uint16_t *outSize);

/**
* @brief Finish DH+Base64 encoding.
*
* @param[in] ctx DH encoding context.
*
* @param[in] pathSpec Our derivation path.
*
* @param[in] publicKey Their public key.
*
* @param[out] outBuffer Output buffer, initialization produces cyphertext.
*
* @param[in, out] outSize Size of output buffer. returns the number of new bytes.
*
* @return Error code:
* - SUCCESS on success
* - ERR_REJECTED_BY_POLICY
* - ERR_ASSERT for other unexpected errors
*/
__noinline_due_to_stack__ WARN_UNUSED_RESULT uint16_t
dh_encode_finalize(dh_context_t *ctx,
const bip44_path_t *pathSpec,
const public_key_t *publicKey,
uint8_t *outBuffer,
uint16_t *outSize);

/**
* @brief Inplace DH decoding function. Input data is NOT base64 encrypted
*
* @param[in] pathSpec Our derivation path.
*
* @param[in] publicKey Their public key.
*
* @param[out] buffer Output buffer, initialization produces cyphertext.
*
* @param[in, out] size Size of output buffer. returns the number of new bytes.
*
* @return Error code:
* - SUCCESS on success
* - ERR_REJECTED_BY_POLICY
* - ERR_INVALID_DATA
* - ERR_INVALID_HMAC
* - ERR_ASSERT for other unexpected errors
*/
__noinline_due_to_stack__ WARN_UNUSED_RESULT uint16_t dh_decode(bip44_path_t *pathSpec,
public_key_t *publicKey,
uint8_t *buffer,
uint16_t *size);

#ifdef DEVEL
__noinline_due_to_stack__ WARN_UNUSED_RESULT uint16_t dh_encode(bip44_path_t *pathSpec,
public_key_t *publicKey,
const uint8_t *iv,
uint16_t ivSize,
const uint8_t *inBuffer,
uint16_t inSize,
uint8_t *outBuffer,
uint16_t *outSize);

__noinline_due_to_stack__ void run_diffieHellman_test();
#endif // DEVEL

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