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feat: support signed execution

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Author: aPere3 <alexandre.pere@zama.ai>
Co-authored-by: Umut <umutsahin@protonmail.com>
This commit is contained in:
aPere3
2022-09-14 10:35:19 +02:00
committed by Quentin Bourgerie
parent f913c39e5b
commit e95c53f2ff
37 changed files with 1092 additions and 184 deletions
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61
compiler/lib/ClientLib/KeySet.cpp
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@@ -355,37 +355,62 @@ KeySet::decrypt_lwe(size_t argPos, uint64_t *ciphertext, uint64_t &output) {
if (!encryption.hasValue()) {
return StringError("decrypt_lwe: the positional argument is not encrypted");
}
auto crt = encryption->encoding.crt;
// CRT encoding - N blocks with crt encoding
if (!crt.empty()) {
if (!crt.empty()) { // The ciphertext used the crt strategy.
// Decrypt and decode remainders
std::vector<int64_t> remainders;
// decrypt and decode remainders
for (auto modulus : crt) {
uint64_t decrypted;
CAPI_ASSERT_ERROR(
default_engine_decrypt_lwe_ciphertext_u64_raw_ptr_buffers(
engine, lweSecretKey, ciphertext, &decrypted));
auto plaintext = crt::decode(decrypted, modulus);
remainders.push_back(plaintext);
ciphertext = ciphertext + lweSecretKeyParam.lweSize();
}
// compute the inverse crt
// Compute the inverse crt
output = crt::iCrt(crt, remainders);
return outcome::success();
// Further decode signed integers
if (encryption->encoding.isSigned) {
uint64_t maxPos = 1;
for (auto prime : encryption->encoding.crt) {
maxPos *= prime;
}
maxPos /= 2;
if (output >= maxPos) {
output -= maxPos * 2;
}
}
} else { // The ciphertext used the scalar strategy
// Decrypt
uint64_t plaintext;
CAPI_ASSERT_ERROR(default_engine_decrypt_lwe_ciphertext_u64_raw_ptr_buffers(
engine, lweSecretKey, ciphertext, &plaintext));
// Decode unsigned integer
uint64_t precision = encryption->encoding.precision;
output = plaintext >> (64 - precision - 2);
auto carry = output % 2;
uint64_t mod = (((uint64_t)1) << (precision + 1));
output = ((output >> 1) + carry) % mod;
// Further decode signed integers.
if (encryption->encoding.isSigned) {
uint64_t maxPos = (((uint64_t)1) << (precision - 1));
if (output >= maxPos) { // The output is actually negative.
// Set the preceding bits to zero
output |= UINT64_MAX << precision;
// This makes sure when the value is cast to int64, it has the correct
// value
};
}
}
// Simple TFHE integers - 1 blocks with one padding bits
uint64_t plaintext;
CAPI_ASSERT_ERROR(default_engine_decrypt_lwe_ciphertext_u64_raw_ptr_buffers(
engine, lweSecretKey, ciphertext, &plaintext));
// Decode
uint64_t precision = encryption->encoding.precision;
output = plaintext >> (64 - precision - 2);
auto carry = output % 2;
uint64_t mod = (((uint64_t)1) << (precision + 1));
output = ((output >> 1) + carry) % mod;
return outcome::success();
}