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#include "lix/libutil/charptr-cast.hh"
#include "lix/libstore/crypto.hh"
#include "lix/libutil/file-system.hh"
#include "lix/libstore/globals.hh"
#include "lix/libutil/strings.hh"
#include <openssl/err.h>
namespace nix {
constexpr size_t ED25519_KEY_BYTES = 32;
constexpr size_t ED25519_SIGNATURE_BYTES = 64;
constexpr size_t MAX_ERROR_MESSAGE_LENGTH = 256;
using EvpPkeyCtxPtr = std::unique_ptr<EVP_PKEY_CTX, decltype([](auto ctx) { EVP_PKEY_CTX_free(ctx); })>;
using EvpSignaturePtr = std::unique_ptr<EVP_SIGNATURE, decltype([](auto alg) { EVP_SIGNATURE_free(alg); })>;
static std::pair<std::string_view, std::string> split(std::string_view s)
{
size_t colon = s.find(':');
if (colon == std::string::npos || colon == 0)
return {"", ""};
return {s.substr(0, colon), base64Decode(s.substr(colon + 1))};
}
std::string openssl_error()
{
auto error = ERR_get_error();
char buf[MAX_ERROR_MESSAGE_LENGTH];
ERR_error_string_n(error, buf, MAX_ERROR_MESSAGE_LENGTH);
return buf;
}
SecretKey::SecretKey(std::string name, EvpPkeyPtr pkey)
: name(std::move(name)), pkey(std::move(pkey))
{}
SecretKey::~SecretKey() = default;
std::string SecretKey::signDetached(std::string_view data) const
{
EVP_PKEY_CTX *ctx = EVP_PKEY_CTX_new(pkey.get(), nullptr);
if (!ctx)
throw Error("signing failed: %s", openssl_error());
EvpPkeyCtxPtr pctx(ctx);
EVP_SIGNATURE *alg = EVP_SIGNATURE_fetch(nullptr, "ED25519", nullptr);
if (!alg)
throw Error("signing failed: %s", openssl_error());
EvpSignaturePtr palg(alg);
if (EVP_PKEY_sign_message_init(pctx.get(), palg.get(), nullptr) != 1)
throw Error("signing failed: %s", openssl_error());
unsigned char sig[ED25519_SIGNATURE_BYTES];
size_t sig_bytes = ED25519_SIGNATURE_BYTES;
if (EVP_PKEY_sign(
pctx.get(),
sig,
&sig_bytes,
// NOLINTNEXTLINE(bugprone-suspicious-stringview-data-usage)
charptr_cast<const unsigned char *>(data.data()),
data.size()
) != 1)
throw Error("signing failed: %s", openssl_error());
assert(sig_bytes == ED25519_SIGNATURE_BYTES);
return fmt("%s:%s", name, base64Encode({charptr_cast<char *>(sig), ED25519_SIGNATURE_BYTES}));
}
PublicKey SecretKey::toPublicKey() const
{
unsigned char raw[ED25519_KEY_BYTES];
size_t key_bytes = ED25519_KEY_BYTES;
assert(EVP_PKEY_get_raw_public_key(pkey.get(), raw, &key_bytes) == 1);
assert(key_bytes == ED25519_KEY_BYTES);
return PublicKey::fromRaw(name, {charptr_cast<char *>(raw), ED25519_KEY_BYTES});
}
std::string SecretKey::to_string() const
{
// For compatibility reasons, the public key is included, even though it is redundant.
unsigned char keys[2 * ED25519_KEY_BYTES];
size_t key_bytes = ED25519_KEY_BYTES;
assert(EVP_PKEY_get_raw_private_key(pkey.get(), keys, &key_bytes) == 1);
assert(key_bytes == ED25519_KEY_BYTES);
assert(EVP_PKEY_get_raw_public_key(pkey.get(), keys + ED25519_KEY_BYTES, &key_bytes) == 1);
assert(key_bytes == ED25519_KEY_BYTES);
return fmt("%s:%s", name, base64Encode({charptr_cast<char *>(keys), 2 * ED25519_KEY_BYTES}));
}
SecretKey SecretKey::generate(std::string_view name)
{
EVP_PKEY *key = EVP_PKEY_Q_keygen(nullptr, nullptr, "ED25519");
if (!key)
throw Error("key generation failed: %s", openssl_error());
EvpPkeyPtr pkey(key);
return SecretKey(std::string(name), std::move(pkey));
}
SecretKey SecretKey::parse(std::string_view s)
{
auto [name, raw_key] = split(s);
// For compatibility reasons, the public key is included, even though it is redundant.
if (raw_key.size() != 2 * ED25519_KEY_BYTES)
throw Error("secret key is not valid");
EVP_PKEY *key = EVP_PKEY_new_raw_private_key(
EVP_PKEY_ED25519,
nullptr,
// NOLINTNEXTLINE(bugprone-suspicious-stringview-data-usage)
charptr_cast<const unsigned char *>(raw_key.data()),
ED25519_KEY_BYTES
);
if (!key)
throw Error("secret key is not valid: %s", openssl_error());
EvpPkeyPtr pkey(key);
// Verify that the redundant copy of the public key is correct.
unsigned char pk[ED25519_KEY_BYTES];
size_t key_bytes = ED25519_KEY_BYTES;
assert(EVP_PKEY_get_raw_public_key(pkey.get(), pk, &key_bytes) == 1);
assert(key_bytes == ED25519_KEY_BYTES);
if (memcmp(pk, raw_key.data() + ED25519_KEY_BYTES, ED25519_KEY_BYTES) != 0)
throw Error("secret key is not valid");
return SecretKey(std::string(name), std::move(pkey));
}
PublicKey::PublicKey(std::string name, EvpPkeyPtr pkey)
: name(std::move(name)), pkey(std::move(pkey))
{}
PublicKey::~PublicKey() = default;
bool PublicKey::verifyDetached(std::string_view data, std::string_view sig) const
{
if (sig.size() != ED25519_SIGNATURE_BYTES)
throw Error("signature is not valid");
EVP_PKEY_CTX *ctx = EVP_PKEY_CTX_new(pkey.get(), nullptr);
if (!ctx)
throw Error("signature verification failed: %s", openssl_error());
EvpPkeyCtxPtr pctx(ctx);
EVP_SIGNATURE *alg = EVP_SIGNATURE_fetch(nullptr, "ED25519", nullptr);
if (!alg)
throw Error("signature verification failed: %s", openssl_error());
EvpSignaturePtr palg(alg);
if (EVP_PKEY_verify_message_init(pctx.get(), palg.get(), nullptr) != 1)
throw Error("signature verification failed: %s", openssl_error());
int result = EVP_PKEY_verify(
pctx.get(),
// NOLINTNEXTLINE(bugprone-suspicious-stringview-data-usage)
charptr_cast<const unsigned char *>(sig.data()),
ED25519_SIGNATURE_BYTES,
// NOLINTNEXTLINE(bugprone-suspicious-stringview-data-usage)
charptr_cast<const unsigned char *>(data.data()),
data.size()
);
switch (result) {
case 1:
// success
return true;
case 0:
// signature did not verify
return false;
default:
// negative return value indicates more serious error
throw Error("signature verification failed: %s", openssl_error());
}
}
std::string PublicKey::to_string() const
{
unsigned char pk[ED25519_KEY_BYTES];
size_t key_bytes = ED25519_KEY_BYTES;
assert(EVP_PKEY_get_raw_public_key(pkey.get(), pk, &key_bytes) == 1);
assert(key_bytes == ED25519_KEY_BYTES);
return fmt("%s:%s", name, base64Encode({charptr_cast<char *>(pk), ED25519_KEY_BYTES}));
}
PublicKey PublicKey::fromRaw(std::string_view name, std::string_view raw)
{
if (raw.size() != ED25519_KEY_BYTES)
throw Error("public key is not valid");
EVP_PKEY *key = EVP_PKEY_new_raw_public_key(
EVP_PKEY_ED25519,
nullptr,
// NOLINTNEXTLINE(bugprone-suspicious-stringview-data-usage)
charptr_cast<const unsigned char *>(raw.data()),
ED25519_KEY_BYTES
);
if (!key)
throw Error("public key is not valid: %s", openssl_error());
EvpPkeyPtr pkey(key);
return PublicKey(std::string(name), std::move(pkey));
}
PublicKey PublicKey::parse(std::string_view s)
{
auto [name, raw] = split(s);
return PublicKey::fromRaw(name, raw);
}
bool verifyDetached(const std::string & data, const std::string & sig,
const PublicKeys & publicKeys)
{
auto [name, sig2] = split(sig);
auto key = publicKeys.find(std::string(name));
if (key == publicKeys.end()) return false;
return key->second.verifyDetached(data, sig2);
}
PublicKeys getDefaultPublicKeys()
{
PublicKeys publicKeys;
// FIXME: filter duplicates
for (auto s : settings.trustedPublicKeys.get()) {
auto key = PublicKey::parse(s);
auto name = key.name;
publicKeys.emplace(name, std::move(key));
}
for (auto secretKeyFile : settings.secretKeyFiles.get()) {
try {
auto secretKey = SecretKey::parse(readFile(secretKeyFile));
publicKeys.emplace(secretKey.name, secretKey.toPublicKey());
} catch (SysError & e) {
/* Ignore unreadable key files. That's normal in a
multi-user installation. */
}
}
return publicKeys;
}
}
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