Identity Credential: Switch default implementation to use libeic.

Introduce platform-neutral C library ("libeic") which can be used to
implement an Identity Credential Trusted Application/Applet in Secure
Hardware.

The libeic library is intentionally low-level, has no dependencies
(not even libc), uses very little run-time memory (less than 500 bytes
during a provisioning or presentation session), and doesn't
dynamically allocate any memory. Crypto routines are provided by the
library user through a simple crypto interface defined in EicOps.

Also provide an Android-side HAL implementation designed to
communicate with libeic running in Secure Hardware outside
Android. Abstract out communications between HAL and TA in a couple of
SecureHardwareProxy* classes which mimic libeic 1:1.

The default implementation of the HAL is a combination of the
aforementioned HAL using libeic in-process backed by BoringSSL for the
crypto bits.

Test: atest VtsHalIdentityTargetTest
Test: atest android.security.identity.cts
Bug: 170146643
Change-Id: I3bf43fa7fd9362f94023052591801f2094a04607

1 files changed, 299 insertions, 0 deletions

diff --git a/identity/aidl/default/libeic/EicOps.h b/identity/aidl/default/libeic/EicOps.h
new file mode 100644
index 0000000000..da4dabf879
--- /dev/null
+++ b/identity/aidl/default/libeic/EicOps.h
@@ -0,0 +1,299 @@
+/*
+ * Copyright 2020, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#if !defined(EIC_INSIDE_LIBEIC_H) && !defined(EIC_COMPILATION)
+#error "Never include this file directly, include libeic.h instead."
+#endif
+
+#ifndef ANDROID_HARDWARE_IDENTITY_EIC_OPS_H
+#define ANDROID_HARDWARE_IDENTITY_EIC_OPS_H
+
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+// Uncomment or define if debug messages are needed.
+//
+//#define EIC_DEBUG
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// The following defines must be set to something appropriate
+//
+//   EIC_SHA256_CONTEXT_SIZE - the size of EicSha256Ctx
+//   EIC_HMAC_SHA256_CONTEXT_SIZE - the size of EicHmacSha256Ctx
+//
+// For example, if EicSha256Ctx is implemented using BoringSSL this would be defined
+// as sizeof(SHA256_CTX).
+//
+// We expect the implementation to provide a header file with the name
+// EicOpsImpl.h to do all this.
+//
+#include "EicOpsImpl.h"
+
+#define EIC_SHA256_DIGEST_SIZE 32
+
+// The size of a P-256 private key.
+//
+#define EIC_P256_PRIV_KEY_SIZE 32
+
+// The size of a P-256 public key in uncompressed form.
+//
+// The public key is stored in uncompressed form, first the X coordinate, then
+// the Y coordinate.
+//
+#define EIC_P256_PUB_KEY_SIZE 64
+
+// Size of one of the coordinates in a curve-point.
+//
+#define EIC_P256_COORDINATE_SIZE 32
+
+// The size of an ECSDA signature using P-256.
+//
+// The R and S values are stored here, first R then S.
+//
+#define EIC_ECDSA_P256_SIGNATURE_SIZE 64
+
+#define EIC_AES_128_KEY_SIZE 16
+
+// The following are definitions of implementation functions the
+// underlying platform must provide.
+//
+
+struct EicSha256Ctx {
+    uint8_t reserved[EIC_SHA256_CONTEXT_SIZE];
+};
+typedef struct EicSha256Ctx EicSha256Ctx;
+
+struct EicHmacSha256Ctx {
+    uint8_t reserved[EIC_HMAC_SHA256_CONTEXT_SIZE];
+};
+typedef struct EicHmacSha256Ctx EicHmacSha256Ctx;
+
+#ifdef EIC_DEBUG
+// Debug macro. Don't include a new-line in message.
+//
+#define eicDebug(...)                            \
+    do {                                         \
+        eicPrint("%s:%d: ", __FILE__, __LINE__); \
+        eicPrint(__VA_ARGS__);                   \
+        eicPrint("\n");                          \
+    } while (0)
+#else
+#define eicDebug(...) \
+    do {              \
+    } while (0)
+#endif
+
+// Prints message which should include new-line character. Can be no-op.
+//
+// Don't use this from code, use eicDebug() instead.
+//
+#ifdef EIC_DEBUG
+void eicPrint(const char* format, ...);
+#else
+inline void eicPrint(const char*, ...) {}
+#endif
+
+// Dumps data as pretty-printed hex. Can be no-op.
+//
+#ifdef EIC_DEBUG
+void eicHexdump(const char* message, const uint8_t* data, size_t dataSize);
+#else
+inline void eicHexdump(const char*, const uint8_t*, size_t) {}
+#endif
+
+// Pretty-prints encoded CBOR. Can be no-op.
+//
+// If a byte-string is larger than |maxBStrSize| its contents will not be
+// printed, instead the value of the form "<bstr size=1099016
+// sha1=ef549cca331f73dfae2090e6a37c04c23f84b07b>" will be printed. Pass zero
+// for |maxBStrSize| to disable this.
+//
+#ifdef EIC_DEBUG
+void eicCborPrettyPrint(const uint8_t* cborData, size_t cborDataSize, size_t maxBStrSize);
+#else
+inline void eicCborPrettyPrint(const uint8_t*, size_t, size_t) {}
+#endif
+
+// Memory setting, see memset(3).
+void* eicMemSet(void* s, int c, size_t n);
+
+// Memory copying, see memcpy(3).
+void* eicMemCpy(void* dest, const void* src, size_t n);
+
+// String length, see strlen(3).
+size_t eicStrLen(const char* s);
+
+// Memory compare, see CRYPTO_memcmp(3SSL)
+//
+// It takes an amount of time dependent on len, but independent of the contents of the
+// memory regions pointed to by s1 and s2.
+//
+int eicCryptoMemCmp(const void* s1, const void* s2, size_t n);
+
+// Random number generation.
+bool eicOpsRandom(uint8_t* buf, size_t numBytes);
+
+// If |testCredential| is true, returns the 128-bit AES Hardware-Bound Key (16 bytes).
+//
+// Otherwise returns all zeroes (16 bytes).
+//
+const uint8_t* eicOpsGetHardwareBoundKey(bool testCredential);
+
+// Encrypts |data| with |key| and |additionalAuthenticatedData| using |nonce|,
+// returns the resulting (nonce || ciphertext || tag) in |encryptedData| which
+// must be of size |dataSize| + 28.
+bool eicOpsEncryptAes128Gcm(
+        const uint8_t* key,    // Must be 16 bytes
+        const uint8_t* nonce,  // Must be 12 bytes
+        const uint8_t* data,   // May be NULL if size is 0
+        size_t dataSize,
+        const uint8_t* additionalAuthenticationData,  // May be NULL if size is 0
+        size_t additionalAuthenticationDataSize, uint8_t* encryptedData);
+
+// Decrypts |encryptedData| using |key| and |additionalAuthenticatedData|,
+// returns resulting plaintext in |data| must be of size |encryptedDataSize| - 28.
+//
+// The format of |encryptedData| must be as specified in the
+// encryptAes128Gcm() function.
+bool eicOpsDecryptAes128Gcm(const uint8_t* key,  // Must be 16 bytes
+                            const uint8_t* encryptedData, size_t encryptedDataSize,
+                            const uint8_t* additionalAuthenticationData,
+                            size_t additionalAuthenticationDataSize, uint8_t* data);
+
+// Creates an EC key using the P-256 curve. The private key is written to
+// |privateKey|. The public key is written to |publicKey|.
+//
+bool eicOpsCreateEcKey(uint8_t privateKey[EIC_P256_PRIV_KEY_SIZE],
+                       uint8_t publicKey[EIC_P256_PUB_KEY_SIZE]);
+
+// Generates CredentialKey plus an attestation certificate.
+//
+// The attestation certificate will be signed by the attestation keys the secure
+// area has been provisioned with. The given |challenge| and |applicationId|
+// will be used as will |testCredential|.
+//
+// The generated certificate will be in X.509 format and returned in |cert|
+// and |certSize| must be set to the size of this array and this function will
+// set it to the size of the certification chain on successfully return.
+//
+// This may return either a single certificate or an entire certificate
+// chain. If it returns only a single certificate, the implementation of
+// SecureHardwareProvisioningProxy::createCredentialKey() should amend the
+// remainder of the certificate chain on the HAL side.
+//
+bool eicOpsCreateCredentialKey(uint8_t privateKey[EIC_P256_PRIV_KEY_SIZE], const uint8_t* challenge,
+                               size_t challengeSize, const uint8_t* applicationId,
+                               size_t applicationIdSize, bool testCredential, uint8_t* cert,
+                               size_t* certSize);  // inout
+
+// Generate an X.509 certificate for the key identified by |publicKey| which
+// must be of the form returned by eicOpsCreateEcKey().
+//
+// The certificate will be signed by the key identified by |signingKey| which
+// must be of the form returned by eicOpsCreateEcKey().
+//
+bool eicOpsSignEcKey(const uint8_t publicKey[EIC_P256_PUB_KEY_SIZE],
+                     const uint8_t signingKey[EIC_P256_PRIV_KEY_SIZE], unsigned int serial,
+                     const char* issuerName, const char* subjectName, time_t validityNotBefore,
+                     time_t validityNotAfter, uint8_t* cert,
+                     size_t* certSize);  // inout
+
+// Uses |privateKey| to create an ECDSA signature of some data (the SHA-256 must
+// be given by |digestOfData|). Returns the signature in |signature|.
+//
+bool eicOpsEcDsa(const uint8_t privateKey[EIC_P256_PRIV_KEY_SIZE],
+                 const uint8_t digestOfData[EIC_SHA256_DIGEST_SIZE],
+                 uint8_t signature[EIC_ECDSA_P256_SIGNATURE_SIZE]);
+
+// Performs Elliptic Curve Diffie-Helman.
+//
+bool eicOpsEcdh(const uint8_t publicKey[EIC_P256_PUB_KEY_SIZE],
+                const uint8_t privateKey[EIC_P256_PRIV_KEY_SIZE],
+                uint8_t sharedSecret[EIC_P256_COORDINATE_SIZE]);
+
+// Performs HKDF.
+//
+bool eicOpsHkdf(const uint8_t* sharedSecret, size_t sharedSecretSize, const uint8_t* salt,
+                size_t saltSize, const uint8_t* info, size_t infoSize, uint8_t* output,
+                size_t outputSize);
+
+// SHA-256 functions.
+void eicOpsSha256Init(EicSha256Ctx* ctx);
+void eicOpsSha256Update(EicSha256Ctx* ctx, const uint8_t* data, size_t len);
+void eicOpsSha256Final(EicSha256Ctx* ctx, uint8_t digest[EIC_SHA256_DIGEST_SIZE]);
+
+// HMAC SHA-256 functions.
+void eicOpsHmacSha256Init(EicHmacSha256Ctx* ctx, const uint8_t* key, size_t keySize);
+void eicOpsHmacSha256Update(EicHmacSha256Ctx* ctx, const uint8_t* data, size_t len);
+void eicOpsHmacSha256Final(EicHmacSha256Ctx* ctx, uint8_t digest[EIC_SHA256_DIGEST_SIZE]);
+
+// Extracts the public key in the given X.509 certificate.
+//
+// If the key is not an EC key, this function fails.
+//
+// Otherwise the public key is stored in uncompressed form in |publicKey| which
+// size should be set in |publicKeySize|. On successful return |publicKeySize|
+// is set to the length of the key. If there is not enough space, the function
+// fails.
+//
+// (The public key returned is not necessarily a P-256 key, even if it is note
+// that its size is not EIC_P256_PUBLIC_KEY_SIZE because of the leading 0x04.)
+//
+bool eicOpsX509GetPublicKey(const uint8_t* x509Cert, size_t x509CertSize, uint8_t* publicKey,
+                            size_t* publicKeySize);
+
+// Checks that the X.509 certificate given by |x509Cert| is signed by the public
+// key given by |publicKey| which must be an EC key in uncompressed form (e.g.
+// same formatt as returned by eicOpsX509GetPublicKey()).
+//
+bool eicOpsX509CertSignedByPublicKey(const uint8_t* x509Cert, size_t x509CertSize,
+                                     const uint8_t* publicKey, size_t publicKeySize);
+
+// Checks that |signature| is a signature of some data (given by |digest|),
+// signed by the public key given by |publicKey|.
+//
+// The key must be an EC key in uncompressed form (e.g.  same format as returned
+// by eicOpsX509GetPublicKey()).
+//
+// The format of the signature is the same encoding as the 'signature' field of
+// COSE_Sign1 - that is, it's the R and S integers both with the same length as
+// the key-size.
+//
+// The size of digest must match the size of the key.
+//
+bool eicOpsEcDsaVerifyWithPublicKey(const uint8_t* digest, size_t digestSize,
+                                    const uint8_t* signature, size_t signatureSize,
+                                    const uint8_t* publicKey, size_t publicKeySize);
+
+// Validates that the passed in data constitutes a valid auth- and verification tokens.
+//
+bool eicOpsValidateAuthToken(uint64_t challenge, uint64_t secureUserId, uint64_t authenticatorId,
+                             int hardwareAuthenticatorType, uint64_t timeStamp, const uint8_t* mac,
+                             size_t macSize, uint64_t verificationTokenChallenge,
+                             uint64_t verificationTokenTimeStamp,
+                             int verificationTokenSecurityLevel,
+                             const uint8_t* verificationTokenMac, size_t verificationTokenMacSize);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // ANDROID_HARDWARE_IDENTITY_EIC_OPS_H