GCC Code Coverage Report

Directory: ./
File: Svc/Ccsds/AesGcmEncryptor/AesGcmEncryptor.cpp
Date: 2026-09-23 21:11:01
Exec Total Coverage
Lines: 76 80 95.0%
Functions: 5 5 100.0%
Branches: 55 67 82.1%
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1 // ======================================================================
2 // \title AesGcmEncryptor.cpp
3 // \author cadena and claradavisb
4 // \brief cpp file for AesGcmEncryptor component implementation class
5 // ======================================================================
6
7 #include "Svc/Ccsds/AesGcmEncryptor/AesGcmEncryptor.hpp"
8 #include "Svc/Ccsds/Utils/SdlsAuthMask.hpp"
9
10 #include <openssl/crypto.h>
11 #include <openssl/evp.h>
12 #include <openssl/rand.h>
13
14 namespace Svc {
15
16 namespace Ccsds {
17
18 //! Length of the AES-GCM initialization vector, in bytes
19 static constexpr U32 GCM_IV_LEN = 12;
20 //! Length of the AES-GCM authentication tag (the SDLS MAC), in bytes
21 static constexpr U32 GCM_TAG_LEN = 16;
22 //! Length of an AES-256 key, in bytes
23 static constexpr FwSizeType AES_256_KEY_LEN = 32;
24
25 // ----------------------------------------------------------------------
26 // Component construction and destruction
27 // ----------------------------------------------------------------------
28
29 // Build the cipher state once so that encrypting a frame allocates nothing.
30 // Only the key and the IV change, and those are supplied per
31 // frame by a single EVP_EncryptInit_ex.
32 13 AesGcmEncryptor ::AesGcmEncryptor(const char* const compName)
33 : AesGcmEncryptorComponentBase(compName),
34
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 13325 m_outBuf(),
35 13 m_bufferState(BufferOwnershipState::OWNED),
36 13 m_cipher(nullptr),
37 13 m_ctx(nullptr),
38 13 m_aad(0, 0),
39 13 m_aadVcId(0),
40 26 m_aadSaIndex(0) {
41
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 13 this->m_cipher = EVP_CIPHER_fetch(nullptr, "AES-256-GCM", nullptr);
42 13 FW_ASSERT(this->m_cipher != nullptr);
43
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 13 this->m_ctx = EVP_CIPHER_CTX_new();
44 13 FW_ASSERT(this->m_ctx != nullptr);
45
46
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 13 int status = EVP_EncryptInit_ex(this->m_ctx, this->m_cipher, nullptr, nullptr, nullptr);
47 13 FW_ASSERT(status == 1, static_cast<FwAssertArgType>(status));
48
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 13 status = EVP_CIPHER_CTX_ctrl(this->m_ctx, EVP_CTRL_GCM_SET_IVLEN, static_cast<int>(GCM_IV_LEN), nullptr);
49 13 FW_ASSERT(status == 1, static_cast<FwAssertArgType>(status));
50 13 }
51
52 26 AesGcmEncryptor ::~AesGcmEncryptor() {
53 26 EVP_CIPHER_CTX_free(this->m_ctx);
54 26 EVP_CIPHER_free(this->m_cipher);
55 26 }
56
57 // ----------------------------------------------------------------------
58 // Handler implementations for typed input ports
59 // ----------------------------------------------------------------------
60
61 19 void AesGcmEncryptor ::encryptIn_handler(FwIndexType portNum,
62 U16 securityAssociationIndex,
63 Fw::Buffer& data,
64 const ComCfg::FrameContext& context) {
65 19 FW_ASSERT(this->m_ctx != nullptr);
66
67 // The previous frame is still downstream and m_outBuf holds ciphertext that has not been
68 // sent. Overwriting it would substitute this frame's contents into the one already in
69 // flight, and the MAC would cover the substitution, so the ground would accept it. Drop
70 // this frame instead
71
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 19 if (this->m_bufferState != BufferOwnershipState::OWNED) {
72
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 1 this->log_WARNING_HI_OutputBufferBusy();
73
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 1 this->failFrame(data, context, Svc::Ccsds::SdlsStatus::ENCRYPTION_FAILURE);
74 1 return;
75 }
76
77 // m_outBuf layout: IV (12) | ciphertext (N) | MAC (16)
78
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 18 const FwSizeType requiredSize = static_cast<FwSizeType>(data.getSize()) + GCM_IV_LEN + GCM_TAG_LEN;
79
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 18 if (requiredSize > MAX_OUTPUT_SIZE) {
80
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 1 this->failFrame(data, context, Svc::Ccsds::SdlsStatus::ENCRYPTION_FAILURE);
81 1 return;
82 }
83
84
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 17 Svc::Ccsds::SdlsKeyBuffer key;
85
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 17 const Svc::Ccsds::SdlsStatus keyStatus = this->keyGet_out(0, securityAssociationIndex, key);
86
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 17 if ((keyStatus != Svc::Ccsds::SdlsStatus::SUCCESS) || (key.getSize() != AES_256_KEY_LEN)) {
87
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 2 this->failFrame(data, context, Svc::Ccsds::SdlsStatus::KEY_ERROR);
88 2 return;
89 }
90
91 15 U8* const iv = this->m_outBuf;
92 15 U8* const ciphertext = this->m_outBuf + GCM_IV_LEN;
93
94 // A repeated IV under one key breaks GCM, so this generates a new one per frame
95
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 15 if (RAND_bytes(iv, static_cast<int>(GCM_IV_LEN)) != 1) {
96 ✗ this->failFrame(data, context, Svc::Ccsds::SdlsStatus::ENCRYPTION_FAILURE);
97 ✗ return;
98 }
99
100 15 int len = 0;
101 15 int cipherLen = 0;
102 // The AAD mask depends only on the VC and the SA, so it is rebuilt when either changes
103 15 const U8 vcId = context.get_vcId();
104
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 15 if ((vcId != this->m_aadVcId) || (securityAssociationIndex != this->m_aadSaIndex)) {
105 10 this->m_aad = Svc::Ccsds::Utils::SdlsTmAuthMask(vcId, securityAssociationIndex);
106 10 this->m_aadVcId = vcId;
107 10 this->m_aadSaIndex = securityAssociationIndex;
108 }
109
110 // Re-keying the context the constructor built. Passing a null cipher here reuses the
111 // algorithm and IV length already set, which is what keeps this path allocation-free.
112 // The first EVP_EncryptUpdate has a null output, so its input is absorbed as AAD; it must precede the plaintext
113 bool encryptSucceeded =
114
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 15 (EVP_EncryptInit_ex(this->m_ctx, nullptr, nullptr, key.getBuffAddr(), iv) == 1) &&
115
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 15 (EVP_EncryptUpdate(this->m_ctx, nullptr, &len, this->m_aad.bytes,
116
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 30 static_cast<int>(sizeof(this->m_aad.bytes))) == 1) &&
117
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 15 (EVP_EncryptUpdate(this->m_ctx, ciphertext, &len, data.getData(), static_cast<int>(data.getSize())) == 1);
118 // The cipher context holds the key schedule now, so the stack copy is dead.
119 // OPENSSL_cleanse wipes the stack copy to prevent it from being recovered by a memory dump or other attack.
120
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 15 OPENSSL_cleanse(key.getBuffAddr(), key.getCapacity());
121
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 15 if (encryptSucceeded) {
122 15 cipherLen = len;
123
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 15 encryptSucceeded = (EVP_EncryptFinal_ex(this->m_ctx, ciphertext + cipherLen, &len) == 1);
124 }
125
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 15 if (encryptSucceeded) {
126 15 cipherLen += len;
127 // The MAC is written straight into its place in m_outBuf, after the ciphertext
128
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 15 encryptSucceeded = (EVP_CIPHER_CTX_ctrl(this->m_ctx, EVP_CTRL_GCM_GET_TAG, static_cast<int>(GCM_TAG_LEN),
129 15 ciphertext + cipherLen) == 1);
130 }
131
132
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 15 if (!encryptSucceeded) {
133 ✗ this->failFrame(data, context, Svc::Ccsds::SdlsStatus::ENCRYPTION_FAILURE);
134 ✗ return;
135 }
136
137 15 const U32 outLen = GCM_IV_LEN + static_cast<U32>(cipherLen) + GCM_TAG_LEN;
138
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 15 Fw::Buffer cipherBuf(this->m_outBuf, outLen);
139
140 // Marked in flight before it is emitted,
141 // so that a subsequent frame arriving before the return of this one is dropped
142 15 this->m_bufferState = BufferOwnershipState::NOT_OWNED;
143
144 // The plaintext has been copied; hand it back before passing the ciphertext downstream
145
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 15 this->bufferReturnOut_out(0, data, context);
146
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 15 this->encryptOut_out(0, Svc::Ccsds::SdlsStatus::SUCCESS, cipherBuf, context);
147 19 }
148
149 8 void AesGcmEncryptor ::encryptReturnIn_handler(FwIndexType portNum,
150 Fw::Buffer& data,
151 const ComCfg::FrameContext& context) {
152 // A failed frame reported its status with an empty buffer
153
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 8 if (!data.isValid()) {
154 1 return;
155 }
156 // Only m_outBuf is ever emitted on encryptOut, so anything else is a wiring error
157 7 FW_ASSERT(data.getData() == this->m_outBuf);
158 7 FW_ASSERT(this->m_bufferState == BufferOwnershipState::NOT_OWNED,
159 static_cast<FwAssertArgType>(this->m_bufferState));
160 7 this->m_bufferState = BufferOwnershipState::OWNED;
161 }
162
163 // ----------------------------------------------------------------------
164 // Helpers
165 // ----------------------------------------------------------------------
166
167 4 void AesGcmEncryptor ::failFrame(Fw::Buffer& data, const ComCfg::FrameContext& context, Svc::Ccsds::SdlsStatus status) {
168 // Return the plaintext to its sender
169
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 4 this->bufferReturnOut_out(0, data, context);
170 // Svc::Ccsds::CcsdsSdlsFramer still needs a status on encryptIn to release the com status
171 // So a failed frame reports one carrying no data rather than nothing.
172
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 4 Fw::Buffer empty;
173
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 4 this->encryptOut_out(0, status, empty, context);
174 8 }
175
176 } // namespace Ccsds
177
178 } // namespace Svc
179