COSE Usage Examples

The following is a simple sample code for command line console.

>>> from cwt import COSE, COSEKey
>>> ctx = COSE.new(alg_auto_inclusion=True, kid_auto_inclusion=True)
>>> mac_key = COSEKey.from_symmetric_key(alg="HS256", kid="01")
>>> encoded = ctx.encode_and_mac(b"Hello world!", mac_key)
>>> encoded.hex()
'd18443a10105a1044230314c48656c6c6f20776f726c642158205d0b144add282ccaac32a02e0d5eec76928ccadf3623271eb48e9464e2ee03b2'
>>> ctx.decode(encoded, mac_key)
b'Hello world!'

This page shows various examples to use COSE API in this library. Specific examples are as follows:

COSE MAC0

Create a COSE MAC0 message, verify and decode it as follows:

from cwt import COSE, COSEKey

mac_key = COSEKey.from_symmetric_key(alg="HS256", kid="01")
ctx = COSE.new(alg_auto_inclusion=True, kid_auto_inclusion=True)
encoded = ctx.encode_and_mac(b"Hello world!", mac_key)
decoded = ctx.decode(encoded, mac_key)

Algorithms other than HS256 are listed in Supported COSE Algorithms .

Following two samples are other ways of writing the above example:

from cwt import COSE, COSEKey

mac_key = COSEKey.from_symmetric_key(alg="HS256", kid="01")
ctx = COSE.new()
encoded = ctx.encode_and_mac(
    b"Hello world!",
    mac_key,
    protected={"alg": "HS256"},
    unprotected={"kid": "01"},
)
decoded = ctx.decode(encoded, mac_key)

from cwt import COSE, COSEKey

mac_key = COSEKey.from_symmetric_key(alg="HS256", kid="01")
ctx = COSE.new()
encoded = ctx.encode_and_mac(
    b"Hello world!",
    mac_key,
    protected={1: 5},
    unprotected={4: b"01"},
)
decoded = ctx.decode(encoded, mac_key)

COSE MAC

Create a COSE MAC message, verify and decode it as follows:

from cwt import COSE, COSEKey

recipient = Recipient.from_json({"alg": "direct", "kid": "01"})
mac_key = COSEKey.from_symmetric_key(alg="HS512", kid="01")
ctx = COSE.new()
encoded = ctx.encode_and_mac(b"Hello world!", mac_key, recipients=[recipient])
decoded = ctx.decode(encoded, mac_key)

Algorithms other than HS512 are listed in Supported COSE Algorithms .

Following sample is another way of writing the above example:

from cwt import COSE, COSEKey

recipient = Recipient.new(unprotected={"alg": "direct", "kid": "01"})
mac_key = COSEKey.from_symmetric_key(alg="HS512", kid="01")
ctx = COSE.new()
encoded = ctx.encode_and_mac(b"Hello world!", mac_key, recipients=[recipient])
decoded = ctx.decode(encoded, mac_key)

COSE Encrypt0

Create a COSE Encrypt0 message, verify and decode it as follows:

from cwt import COSE, COSEKey

enc_key = COSEKey.from_symmetric_key(alg="ChaCha20/Poly1305", kid="01")
ctx = COSE.new(alg_auto_inclusion=True, kid_auto_inclusion=True)
encoded = ctx.encode_and_encrypt(b"Hello world!", enc_key)
decoded = ctx.decode(encoded, enc_key)

Algorithms other than ChaCha20/Poly1305 are listed in Supported COSE Algorithms .

Following two samples are other ways of writing the above example:

from cwt import COSE, COSEKey

enc_key = COSEKey.from_symmetric_key(alg="ChaCha20/Poly1305", kid="01")
ctx = COSE.new()
encoded = ctx.encode_and_encrypt(
    b"Hello world!",
    enc_key,
    nonce=nonce,
    protected={"alg": "ChaCha20/Poly1305"},
    unprotected={"kid": "01"},
)
decoded = ctx.decode(encoded, enc_key)

from cwt import COSE, COSEKey

enc_key = COSEKey.from_symmetric_key(alg="ChaCha20/Poly1305", kid="01")
ctx = COSE.new()
encoded = ctx.encode_and_encrypt(
    b"Hello world!",
    enc_key,
    nonce=nonce,
    protected={1: 24},
    unprotected={4: b"01"},
)
decoded = ctx.decode(encoded, enc_key)

COSE Encrypt

Create a COSE Encrypt message, verify and decode it as follows:

from cwt import COSE, COSEKey

recipient = Recipient.from_json({"alg": "direct", "kid": "01"})
enc_key = COSEKey.from_symmetric_key(alg="ChaCha20/Poly1305", kid="01")
ctx = COSE.new()
encoded = ctx.encode_and_encrypt(
    b"Hello world!",
    enc_key,
    recipients=[recipient],
)
decoded = ctx.decode(encoded, enc_key)

Following sample is another way of writing the above example:

from cwt import COSE, COSEKey

recipient = Recipient.new(unprotected={"alg": "direct", "kid": "01"})
enc_key = COSEKey.from_symmetric_key(alg="ChaCha20/Poly1305", kid="01")
ctx = COSE.new()
encoded = ctx.encode_and_mac(b"Hello world!", enc_key, recipients=[recipient])
decoded = ctx.decode(encoded, enc_key)

COSE Signature1

Create a COSE Signature1 message, verify and decode it as follows:

from cwt import COSE, COSEKey

sig_key = COSEKey.from_jwk(
    {
        "kty": "EC",
        "kid": "01",
        "crv": "P-256",
        "x": "usWxHK2PmfnHKwXPS54m0kTcGJ90UiglWiGahtagnv8",
        "y": "IBOL-C3BttVivg-lSreASjpkttcsz-1rb7btKLv8EX4",
        "d": "V8kgd2ZBRuh2dgyVINBUqpPDr7BOMGcF22CQMIUHtNM",
    }
)
ctx = COSE.new(alg_auto_inclusion=True, kid_auto_inclusion=True)
encoded = ctx.encode_and_sign(b"Hello world!", sig_key)
decoded = ctx.decode(encoded, sig_key)

Following two samples are other ways of writing the above example:

from cwt import COSE, COSEKey

sig_key = COSEKey.from_jwk(
    {
        "kty": "EC",
        "kid": "01",
        "crv": "P-256",
        "x": "usWxHK2PmfnHKwXPS54m0kTcGJ90UiglWiGahtagnv8",
        "y": "IBOL-C3BttVivg-lSreASjpkttcsz-1rb7btKLv8EX4",
        "d": "V8kgd2ZBRuh2dgyVINBUqpPDr7BOMGcF22CQMIUHtNM",
    }
)
ctx = COSE.new()
encoded = ctx.encode_and_sign(
    b"Hello world!",
    sig_key,
    protected={"alg": "ES256"},
    unprotected={"kid": "01"},
)
decoded = ctx.decode(encoded, sig_key)

from cwt import COSE, COSEKey

sig_key = COSEKey.from_jwk(
    {
        "kty": "EC",
        "kid": "01",
        "crv": "P-256",
        "x": "usWxHK2PmfnHKwXPS54m0kTcGJ90UiglWiGahtagnv8",
        "y": "IBOL-C3BttVivg-lSreASjpkttcsz-1rb7btKLv8EX4",
        "d": "V8kgd2ZBRuh2dgyVINBUqpPDr7BOMGcF22CQMIUHtNM",
    }
)
ctx = COSE.new()
encoded = ctx.encode_and_sign(
    b"Hello world!",
    sig_key,
    protected={1: -7},
    unprotected={4: b"01"},
)
decoded = ctx.decode(encoded, sig_key)

COSE Signature

Create a COSE Signature message, verify and decode it as follows:

from cwt import COSE, Signer

signer = Signer.from_jwk(
    {
        "kty": "EC",
        "kid": "01",
        "crv": "P-256",
        "x": "usWxHK2PmfnHKwXPS54m0kTcGJ90UiglWiGahtagnv8",
        "y": "IBOL-C3BttVivg-lSreASjpkttcsz-1rb7btKLv8EX4",
        "d": "V8kgd2ZBRuh2dgyVINBUqpPDr7BOMGcF22CQMIUHtNM",
    },
)
ctx = COSE.new()
encoded = ctx.encode_and_sign(b"Hello world!", signers=[signer])
decoded = ctx.decode(encoded, signer.cose_key)

Following two samples are other ways of writing the above example:

from cwt import COSE, COSEKey, Signer

signer = Signer.new(
    cose_key=COSEKey.from_jwk(
        {
            "kty": "EC",
            "kid": "01",
            "crv": "P-256",
            "x": "usWxHK2PmfnHKwXPS54m0kTcGJ90UiglWiGahtagnv8",
            "y": "IBOL-C3BttVivg-lSreASjpkttcsz-1rb7btKLv8EX4",
            "d": "V8kgd2ZBRuh2dgyVINBUqpPDr7BOMGcF22CQMIUHtNM",
        }
    ),
    protected={"alg": "ES256"},
    unprotected={"kid": "01"},
)
ctx = COSE.new()
encoded = ctx.encode_and_sign(b"Hello world!", signers=[signer])
decoded = ctx.decode(encoded, signer.cose_key)

from cwt import COSE, COSEKey, Signer

signer = Signer.new(
    cose_key=COSEKey.from_jwk(
        {
            "kty": "EC",
            "kid": "01",
            "crv": "P-256",
            "x": "usWxHK2PmfnHKwXPS54m0kTcGJ90UiglWiGahtagnv8",
            "y": "IBOL-C3BttVivg-lSreASjpkttcsz-1rb7btKLv8EX4",
            "d": "V8kgd2ZBRuh2dgyVINBUqpPDr7BOMGcF22CQMIUHtNM",
        }
    ),
    protected={1: -7},
    unprotected={4: b"01"},
)
ctx = COSE.new()
encoded = ctx.encode_and_sign(b"Hello world!", signers=[signer])
decoded = ctx.decode(encoded, signer.cose_key)