Alice Wang | 600ea5b | 2023-11-17 15:12:16 +0000 | [diff] [blame] | 1 | // Copyright 2023, The Android Open Source Project |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | //! Wrappers of the EVP functions in BoringSSL evp.h. |
| 16 | |
| 17 | use crate::cbb::CbbFixed; |
Alice Wang | 7468ae4 | 2023-11-30 10:20:36 +0000 | [diff] [blame] | 18 | use crate::digest::{Digester, DigesterContext}; |
Alice Wang | 600ea5b | 2023-11-17 15:12:16 +0000 | [diff] [blame] | 19 | use crate::ec_key::EcKey; |
| 20 | use crate::util::{check_int_result, to_call_failed_error}; |
| 21 | use alloc::vec::Vec; |
| 22 | use bssl_avf_error::{ApiName, Result}; |
| 23 | use bssl_ffi::{ |
Alice Wang | 7468ae4 | 2023-11-30 10:20:36 +0000 | [diff] [blame] | 24 | CBB_flush, CBB_len, EVP_DigestVerify, EVP_DigestVerifyInit, EVP_PKEY_free, EVP_PKEY_new, |
| 25 | EVP_PKEY_new_raw_public_key, EVP_PKEY_set1_EC_KEY, EVP_marshal_public_key, EVP_PKEY, |
| 26 | EVP_PKEY_ED25519, EVP_PKEY_X25519, |
Alice Wang | 600ea5b | 2023-11-17 15:12:16 +0000 | [diff] [blame] | 27 | }; |
Alice Wang | 7468ae4 | 2023-11-30 10:20:36 +0000 | [diff] [blame] | 28 | use core::ptr::{self, NonNull}; |
Alice Wang | 600ea5b | 2023-11-17 15:12:16 +0000 | [diff] [blame] | 29 | |
| 30 | /// Wrapper of an `EVP_PKEY` object, representing a public or private key. |
Alice Wang | eb77f7d | 2023-12-01 09:13:58 +0000 | [diff] [blame] | 31 | pub struct PKey { |
Alice Wang | 600ea5b | 2023-11-17 15:12:16 +0000 | [diff] [blame] | 32 | pkey: NonNull<EVP_PKEY>, |
Alice Wang | 7468ae4 | 2023-11-30 10:20:36 +0000 | [diff] [blame] | 33 | /// If this struct owns the inner EC key, the inner EC key should remain valid as |
Alice Wang | 600ea5b | 2023-11-17 15:12:16 +0000 | [diff] [blame] | 34 | /// long as the pointer to `EVP_PKEY` is valid. |
Alice Wang | 7468ae4 | 2023-11-30 10:20:36 +0000 | [diff] [blame] | 35 | _inner_ec_key: Option<EcKey>, |
Alice Wang | 600ea5b | 2023-11-17 15:12:16 +0000 | [diff] [blame] | 36 | } |
| 37 | |
Alice Wang | eb77f7d | 2023-12-01 09:13:58 +0000 | [diff] [blame] | 38 | impl Drop for PKey { |
Alice Wang | 600ea5b | 2023-11-17 15:12:16 +0000 | [diff] [blame] | 39 | fn drop(&mut self) { |
| 40 | // SAFETY: It is safe because `EVP_PKEY` has been allocated by BoringSSL and isn't |
| 41 | // used after this. |
| 42 | unsafe { EVP_PKEY_free(self.pkey.as_ptr()) } |
| 43 | } |
| 44 | } |
| 45 | |
| 46 | /// Creates a new empty `EVP_PKEY`. |
| 47 | fn new_pkey() -> Result<NonNull<EVP_PKEY>> { |
| 48 | // SAFETY: The returned pointer is checked below. |
| 49 | let key = unsafe { EVP_PKEY_new() }; |
| 50 | NonNull::new(key).ok_or(to_call_failed_error(ApiName::EVP_PKEY_new)) |
| 51 | } |
| 52 | |
Alice Wang | eb77f7d | 2023-12-01 09:13:58 +0000 | [diff] [blame] | 53 | impl TryFrom<EcKey> for PKey { |
Alice Wang | 600ea5b | 2023-11-17 15:12:16 +0000 | [diff] [blame] | 54 | type Error = bssl_avf_error::Error; |
| 55 | |
| 56 | fn try_from(key: EcKey) -> Result<Self> { |
| 57 | let pkey = new_pkey()?; |
Alice Wang | 7468ae4 | 2023-11-30 10:20:36 +0000 | [diff] [blame] | 58 | // SAFETY: The function only sets the inner EC key of the initialized and |
Alice Wang | 600ea5b | 2023-11-17 15:12:16 +0000 | [diff] [blame] | 59 | // non-null `EVP_PKEY` to point to the given `EC_KEY`. It only reads from |
| 60 | // and writes to the initialized `EVP_PKEY`. |
| 61 | // Since this struct owns the inner key, the inner key remains valid as |
| 62 | // long as `EVP_PKEY` is valid. |
| 63 | let ret = unsafe { EVP_PKEY_set1_EC_KEY(pkey.as_ptr(), key.0.as_ptr()) }; |
| 64 | check_int_result(ret, ApiName::EVP_PKEY_set1_EC_KEY)?; |
Alice Wang | 7468ae4 | 2023-11-30 10:20:36 +0000 | [diff] [blame] | 65 | Ok(Self { pkey, _inner_ec_key: Some(key) }) |
Alice Wang | 600ea5b | 2023-11-17 15:12:16 +0000 | [diff] [blame] | 66 | } |
| 67 | } |
| 68 | |
Alice Wang | eb77f7d | 2023-12-01 09:13:58 +0000 | [diff] [blame] | 69 | impl PKey { |
Alice Wang | 600ea5b | 2023-11-17 15:12:16 +0000 | [diff] [blame] | 70 | /// Returns a DER-encoded SubjectPublicKeyInfo structure as specified |
| 71 | /// in RFC 5280 s4.1.2.7: |
| 72 | /// |
| 73 | /// https://www.rfc-editor.org/rfc/rfc5280.html#section-4.1.2.7 |
| 74 | pub fn subject_public_key_info(&self) -> Result<Vec<u8>> { |
| 75 | const CAPACITY: usize = 256; |
| 76 | let mut buf = [0u8; CAPACITY]; |
| 77 | let mut cbb = CbbFixed::new(buf.as_mut()); |
| 78 | // SAFETY: The function only write bytes to the buffer managed by the valid `CBB`. |
| 79 | // The inner key in `EVP_PKEY` was set to a valid key when the object was created. |
| 80 | // As this struct owns the inner key, the inner key is guaranteed to be valid |
| 81 | // throughout the execution of the function. |
| 82 | let ret = unsafe { EVP_marshal_public_key(cbb.as_mut(), self.pkey.as_ptr()) }; |
| 83 | check_int_result(ret, ApiName::EVP_marshal_public_key)?; |
| 84 | // SAFETY: This is safe because the CBB pointer is a valid pointer initialized with |
| 85 | // `CBB_init_fixed()`. |
| 86 | check_int_result(unsafe { CBB_flush(cbb.as_mut()) }, ApiName::CBB_flush)?; |
| 87 | // SAFETY: This is safe because the CBB pointer is initialized with `CBB_init_fixed()`, |
| 88 | // and it has been flushed, thus it has no active children. |
| 89 | let len = unsafe { CBB_len(cbb.as_ref()) }; |
| 90 | Ok(buf.get(0..len).ok_or(to_call_failed_error(ApiName::CBB_len))?.to_vec()) |
| 91 | } |
Alice Wang | 7468ae4 | 2023-11-30 10:20:36 +0000 | [diff] [blame] | 92 | |
| 93 | /// This function takes a raw public key data slice and creates a `PKey` instance wrapping |
| 94 | /// a freshly allocated `EVP_PKEY` object from it. |
| 95 | /// |
| 96 | /// The lifetime of the returned instance is not tied to the lifetime of the raw public |
| 97 | /// key slice because the raw data is copied into the `EVP_PKEY` object. |
| 98 | /// |
| 99 | /// Currently the only supported raw formats are X25519 and Ed25519, where the formats |
| 100 | /// are specified in RFC 7748 and RFC 8032 respectively. |
| 101 | pub fn new_raw_public_key(raw_public_key: &[u8], type_: PKeyType) -> Result<Self> { |
| 102 | let engine = ptr::null_mut(); // Engine is not used. |
| 103 | let pkey = |
| 104 | // SAFETY: The function only reads from the given raw public key within its bounds. |
| 105 | // The returned pointer is checked below. |
| 106 | unsafe { |
| 107 | EVP_PKEY_new_raw_public_key( |
| 108 | type_.0, |
| 109 | engine, |
| 110 | raw_public_key.as_ptr(), |
| 111 | raw_public_key.len(), |
| 112 | ) |
| 113 | }; |
| 114 | let pkey = |
| 115 | NonNull::new(pkey).ok_or(to_call_failed_error(ApiName::EVP_PKEY_new_raw_public_key))?; |
| 116 | Ok(Self { pkey, _inner_ec_key: None }) |
| 117 | } |
| 118 | |
| 119 | /// Verifies the given `signature` of the `message` using the current public key. |
| 120 | /// |
| 121 | /// The `message` will be hashed using the given `digester` before verification. |
| 122 | /// |
| 123 | /// For algorithms like Ed25519 that do not use pre-hashed inputs, the `digester` should |
| 124 | /// be `None`. |
| 125 | pub fn verify( |
| 126 | &self, |
| 127 | signature: &[u8], |
| 128 | message: &[u8], |
| 129 | digester: Option<Digester>, |
| 130 | ) -> Result<()> { |
| 131 | let mut digester_context = DigesterContext::new()?; |
| 132 | // The `EVP_PKEY_CTX` is set to null as this function does not collect the context |
| 133 | // during the verification. |
| 134 | let pkey_context = ptr::null_mut(); |
| 135 | let engine = ptr::null_mut(); // Use the default engine. |
| 136 | let ret = |
| 137 | // SAFETY: All the non-null parameters passed to this function have been properly |
| 138 | // initialized as required in the BoringSSL spec. |
| 139 | unsafe { |
| 140 | EVP_DigestVerifyInit( |
| 141 | digester_context.as_mut_ptr(), |
| 142 | pkey_context, |
| 143 | digester.map_or(ptr::null(), |d| d.0), |
| 144 | engine, |
| 145 | self.pkey.as_ptr(), |
| 146 | ) |
| 147 | }; |
| 148 | check_int_result(ret, ApiName::EVP_DigestVerifyInit)?; |
| 149 | |
| 150 | // SAFETY: The function only reads from the given slices within their bounds. |
| 151 | // The `EVP_MD_CTX` is successfully initialized before this call. |
| 152 | let ret = unsafe { |
| 153 | EVP_DigestVerify( |
| 154 | digester_context.as_mut_ptr(), |
| 155 | signature.as_ptr(), |
| 156 | signature.len(), |
| 157 | message.as_ptr(), |
| 158 | message.len(), |
| 159 | ) |
| 160 | }; |
| 161 | check_int_result(ret, ApiName::EVP_DigestVerify) |
| 162 | } |
| 163 | } |
| 164 | |
| 165 | /// Type of the keys supported by `PKey`. |
| 166 | /// |
| 167 | /// It is a wrapper of the `EVP_PKEY_*` macros defined BoringSSL evp.h, which are the |
| 168 | /// NID values of the corresponding keys. |
| 169 | #[derive(Debug, Copy, Clone, PartialEq, Eq)] |
| 170 | pub struct PKeyType(i32); |
| 171 | |
| 172 | impl PKeyType { |
| 173 | /// EVP_PKEY_X25519 / NID_X25519 |
| 174 | pub const X25519: PKeyType = PKeyType(EVP_PKEY_X25519); |
| 175 | /// EVP_PKEY_ED25519 / NID_ED25519 |
| 176 | pub const ED25519: PKeyType = PKeyType(EVP_PKEY_ED25519); |
Alice Wang | 600ea5b | 2023-11-17 15:12:16 +0000 | [diff] [blame] | 177 | } |