Bouncy Castle ECIES compressed format
I am using the bouncy castle ECIES with AES in CBC mode provider to encrypt data:
Cipher iesCipher = Cipher.getInstance("ECIESWITHAES-CBC");
iesCipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte ciphertext = iesCipher.doFinal(plaintext);
This results in a ciphertext with the format:
0x04 || coordinate x || coordinate y || PKCS5 padded ciphertext || 20-byte HMAC-digest
The 0x04 indicates the uncompressed format, where the y coordinate is also stored. Using eg. secp256k1, this results in 32 byte unnecessary overhead.
Now I would like to use the compressed format with 0x02 and 0x03 prefixes.
Unfortunately, I didn't find a specification of the parameters to use to achieve this.
java bouncycastle
asked Nov 26 '18 at 8:36
MarcMarc
3,20282640
add a comment |
I am using the bouncy castle ECIES with AES in CBC mode provider to encrypt data:
Cipher iesCipher = Cipher.getInstance("ECIESWITHAES-CBC");
iesCipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte ciphertext = iesCipher.doFinal(plaintext);
This results in a ciphertext with the format:
0x04 || coordinate x || coordinate y || PKCS5 padded ciphertext || 20-byte HMAC-digest
The 0x04 indicates the uncompressed format, where the y coordinate is also stored. Using eg. secp256k1, this results in 32 byte unnecessary overhead.
Now I would like to use the compressed format with 0x02 and 0x03 prefixes.
Unfortunately, I didn't find a specification of the parameters to use to achieve this.
java bouncycastle
asked Nov 26 '18 at 8:36
MarcMarc
3,20282640
add a comment |
I am using the bouncy castle ECIES with AES in CBC mode provider to encrypt data:
Cipher iesCipher = Cipher.getInstance("ECIESWITHAES-CBC");
iesCipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte ciphertext = iesCipher.doFinal(plaintext);
This results in a ciphertext with the format:
0x04 || coordinate x || coordinate y || PKCS5 padded ciphertext || 20-byte HMAC-digest
The 0x04 indicates the uncompressed format, where the y coordinate is also stored. Using eg. secp256k1, this results in 32 byte unnecessary overhead.
Now I would like to use the compressed format with 0x02 and 0x03 prefixes.
Unfortunately, I didn't find a specification of the parameters to use to achieve this.
java bouncycastle
asked Nov 26 '18 at 8:36
MarcMarc
3,20282640
I am using the bouncy castle ECIES with AES in CBC mode provider to encrypt data:
Cipher iesCipher = Cipher.getInstance("ECIESWITHAES-CBC");
iesCipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte ciphertext = iesCipher.doFinal(plaintext);
This results in a ciphertext with the format:
0x04 || coordinate x || coordinate y || PKCS5 padded ciphertext || 20-byte HMAC-digest
The 0x04 indicates the uncompressed format, where the y coordinate is also stored. Using eg. secp256k1, this results in 32 byte unnecessary overhead.
Now I would like to use the compressed format with 0x02 and 0x03 prefixes.
Unfortunately, I didn't find a specification of the parameters to use to achieve this.
java bouncycastle
java bouncycastle
asked Nov 26 '18 at 8:36
MarcMarc
3,20282640
asked Nov 26 '18 at 8:36
MarcMarc
3,20282640
asked Nov 26 '18 at 8:36
MarcMarc
3,20282640
asked Nov 26 '18 at 8:36
MarcMarc
3,20282640
asked Nov 26 '18 at 8:36
MarcMarc
3,20282640
3,20282640
add a comment |
add a comment |
1 Answer
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I managed to solve this by setting the usePointCompression flag in the BC IESParameterSpec to true.
The point compression flag is false by default.
Unfortunately, this flag is not part of their ECIESTest, so I used their encryption mode configuration (derivation, encoding and initialization vectors) to try out the flag:
byte derivation = Hex.decode("202122232425262728292a2b2c2d2e2f");
byte encoding = Hex.decode("303132333435363738393a3b3c3d3e3f");
byte nonce = Hex.decode("000102030405060708090a0b0c0d0e0f");
Cipher c = Cipher.getInstance("ECIESwithAES-CBC", "BC");
IESParameterSpec params = new IESParameterSpec(derivation, encoding, 128, 128, nonce, true);
c.init(Cipher.ENCRYPT_MODE, publicKey, params);
byte ciphertext = c.doFinal(plaintext);
This results in the desired format:
0x02 || coordinate x || PKCS5 padded ciphertext || 20-byte HMAC-digest
0x03 || coordinate x || PKCS5 padded ciphertext || 20-byte HMAC-digest
Depending on the corresponding y-coordinate (positve/negative).
answered Nov 30 '18 at 8:28
MarcMarc
3,20282640
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
I managed to solve this by setting the usePointCompression flag in the BC IESParameterSpec to true.
The point compression flag is false by default.
Unfortunately, this flag is not part of their ECIESTest, so I used their encryption mode configuration (derivation, encoding and initialization vectors) to try out the flag:
byte derivation = Hex.decode("202122232425262728292a2b2c2d2e2f");
byte encoding = Hex.decode("303132333435363738393a3b3c3d3e3f");
byte nonce = Hex.decode("000102030405060708090a0b0c0d0e0f");
Cipher c = Cipher.getInstance("ECIESwithAES-CBC", "BC");
IESParameterSpec params = new IESParameterSpec(derivation, encoding, 128, 128, nonce, true);
c.init(Cipher.ENCRYPT_MODE, publicKey, params);
byte ciphertext = c.doFinal(plaintext);
This results in the desired format:
0x02 || coordinate x || PKCS5 padded ciphertext || 20-byte HMAC-digest
0x03 || coordinate x || PKCS5 padded ciphertext || 20-byte HMAC-digest
Depending on the corresponding y-coordinate (positve/negative).
answered Nov 30 '18 at 8:28
MarcMarc
3,20282640
add a comment |
I managed to solve this by setting the usePointCompression flag in the BC IESParameterSpec to true.
The point compression flag is false by default.
Unfortunately, this flag is not part of their ECIESTest, so I used their encryption mode configuration (derivation, encoding and initialization vectors) to try out the flag:
byte derivation = Hex.decode("202122232425262728292a2b2c2d2e2f");
byte encoding = Hex.decode("303132333435363738393a3b3c3d3e3f");
byte nonce = Hex.decode("000102030405060708090a0b0c0d0e0f");
Cipher c = Cipher.getInstance("ECIESwithAES-CBC", "BC");
IESParameterSpec params = new IESParameterSpec(derivation, encoding, 128, 128, nonce, true);
c.init(Cipher.ENCRYPT_MODE, publicKey, params);
byte ciphertext = c.doFinal(plaintext);
This results in the desired format:
0x02 || coordinate x || PKCS5 padded ciphertext || 20-byte HMAC-digest
0x03 || coordinate x || PKCS5 padded ciphertext || 20-byte HMAC-digest
Depending on the corresponding y-coordinate (positve/negative).
answered Nov 30 '18 at 8:28
MarcMarc
3,20282640
add a comment |
I managed to solve this by setting the usePointCompression flag in the BC IESParameterSpec to true.
The point compression flag is false by default.
Unfortunately, this flag is not part of their ECIESTest, so I used their encryption mode configuration (derivation, encoding and initialization vectors) to try out the flag:
byte derivation = Hex.decode("202122232425262728292a2b2c2d2e2f");
byte encoding = Hex.decode("303132333435363738393a3b3c3d3e3f");
byte nonce = Hex.decode("000102030405060708090a0b0c0d0e0f");
Cipher c = Cipher.getInstance("ECIESwithAES-CBC", "BC");
IESParameterSpec params = new IESParameterSpec(derivation, encoding, 128, 128, nonce, true);
c.init(Cipher.ENCRYPT_MODE, publicKey, params);
byte ciphertext = c.doFinal(plaintext);
This results in the desired format:
0x02 || coordinate x || PKCS5 padded ciphertext || 20-byte HMAC-digest
0x03 || coordinate x || PKCS5 padded ciphertext || 20-byte HMAC-digest
Depending on the corresponding y-coordinate (positve/negative).
answered Nov 30 '18 at 8:28
MarcMarc
3,20282640
I managed to solve this by setting the usePointCompression flag in the BC IESParameterSpec to true.
The point compression flag is false by default.
Unfortunately, this flag is not part of their ECIESTest, so I used their encryption mode configuration (derivation, encoding and initialization vectors) to try out the flag:
byte derivation = Hex.decode("202122232425262728292a2b2c2d2e2f");
byte encoding = Hex.decode("303132333435363738393a3b3c3d3e3f");
byte nonce = Hex.decode("000102030405060708090a0b0c0d0e0f");
Cipher c = Cipher.getInstance("ECIESwithAES-CBC", "BC");
IESParameterSpec params = new IESParameterSpec(derivation, encoding, 128, 128, nonce, true);
c.init(Cipher.ENCRYPT_MODE, publicKey, params);
byte ciphertext = c.doFinal(plaintext);
This results in the desired format:
0x02 || coordinate x || PKCS5 padded ciphertext || 20-byte HMAC-digest
0x03 || coordinate x || PKCS5 padded ciphertext || 20-byte HMAC-digest
Depending on the corresponding y-coordinate (positve/negative).
answered Nov 30 '18 at 8:28
MarcMarc
3,20282640
answered Nov 30 '18 at 8:28
MarcMarc
3,20282640
answered Nov 30 '18 at 8:28
MarcMarc
3,20282640
answered Nov 30 '18 at 8:28
MarcMarc
3,20282640
3,20282640
add a comment |
add a comment |
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