FIDO2-CRED(1) General Commands Manual FIDO2-CRED(1)
NAME
fido2-cred — make/verify a FIDO2 credential
SYNOPSIS
fido2-cred −M
[−bdhqruvw]
[−c cred_protect]
[−i input_file]
[−o output_file] device
[type]
fido2-cred −V [−dhv]
[−c cred_protect]
[−i input_file]
[−o output_file] [type]
DESCRIPTION
fido2-cred makes or verifies a FIDO2 credential.
A credential type may be es256 (denoting ECDSA over NIST P-256 with SHA-256), rs256 (denoting 2048-bit RSA with PKCS#1.5 padding and SHA-256), or eddsa (denoting EDDSA over Curve25519 with SHA-512). If type is not specified, es256 is assumed.
When making a credential, the authenticator may require the user to authenticate with a PIN. If the −q option is not specified, fido2-cred will prompt the user for the PIN. If a tty is available, fido2-cred will use it to obtain the PIN. Otherwise, stdin is used.
The input of fido2-cred is defined by the parameters of the credential to be made/verified. See the “INPUT FORMAT” section for details.
The output of fido2-cred is defined by the result of the selected operation. See the “OUTPUT FORMAT” section for details.
If a credential is successfully created or verified, fido2-cred exits 0. Otherwise, fido2-cred exits 1.
The options are as follows:
−M
Tells fido2-cred to make a new credential on device.
−V
Tells fido2-cred to verify a credential.
−b
Request the credential’s “largeBlobKey”, a 32-byte symmetric key associated with the generated credential.
−c cred_protect
If making a credential, set the credential’s protection level to cred_protect, where cred_protect is the credential’s protection level in decimal notation. Please refer to <fido/param.h> for the set of possible values. If verifying a credential, check whether the credential’s protection level was signed by the authenticator as cred_protect.
−d
Causes fido2-cred to emit debugging output on stderr.
−h
If making a credential, enable the FIDO2 hmac-secret extension. If verifying a credential, check whether the extension data bit was signed by the authenticator.
−i input_file
Tells fido2-cred to read the parameters of the credential from input_file instead of stdin.
−o output_file
Tells fido2-cred to write output on output_file instead of stdout.
−q
Tells fido2-cred to be quiet. If a PIN is required and −q is specified, fido2-cred will fail.
−r
Create a resident credential. Resident credentials are called “discoverable credentials” in CTAP 2.1.
−u
Create a U2F credential. By default, fido2-cred will use FIDO2 if supported by the authenticator, and fallback to U2F otherwise.
−v
If making a credential, request user verification. If verifying a credential, check whether the user verification bit was signed by the authenticator.
−w
Tells fido2-cred that the first line of input when making a credential shall be interpreted as unhashed client data. This is required by Windows Hello, which calculates the client data hash internally.
INPUT FORMAT
The input of fido2-cred consists of base64 blobs and UTF-8 strings separated by newline characters (’\n’).
When making a credential, fido2-cred expects its input to consist of:
1.
client data hash (base64 blob);
2.
relying party id (UTF-8 string);
3.
user name (UTF-8 string);
4.
user id (base64 blob).
When verifying a credential, fido2-cred expects its input to consist of:
1.
client data hash (base64 blob);
2.
relying party id (UTF-8 string);
3.
credential format (UTF-8 string);
4.
authenticator data (base64 blob);
5.
credential id (base64 blob);
6.
attestation signature (base64 blob);
7.
attestation certificate (optional, base64 blob).
UTF-8 strings passed to fido2-cred must not contain embedded newline or NUL characters.
OUTPUT FORMAT
The output of fido2-cred consists of base64 blobs, UTF-8 strings, and PEM-encoded public keys separated by newline characters (’\n’).
Upon the successful generation of a credential, fido2-cred outputs:
1.
client data hash (base64 blob);
2.
relying party id (UTF-8 string);
3.
credential format (UTF-8 string);
4.
authenticator data (base64 blob);
5.
credential id (base64 blob);
6.
attestation signature (base64 blob);
7.
attestation certificate, if present (base64 blob).
8.
the credential’s associated 32-byte symmetric key (“largeBlobKey”), if present (base64 blob).
Upon the successful verification of a credential, fido2-cred outputs:
1.
credential id (base64 blob);
2.
PEM-encoded credential key.
EXAMPLES
Create a new es256 credential on /dev/hidraw5, verify it, and save the id and the public key of the credential in cred:
$ echo
credential challenge | openssl sha256 -binary |
base64 > cred_param
$ echo relying party >> cred_param
$ echo user name >> cred_param
$ dd if=/dev/urandom bs=1 count=32 | base64 >>
cred_param
$ fido2-cred -M -i cred_param /dev/hidraw5 |
fido2-cred -V -o cred
SEE ALSO
fido2-assert(1), fido2-token(1)
CAVEATS
Please note that fido2-cred handles Basic Attestation and Self Attestation transparently. In the case of Basic Attestation, the validity of the authenticator’s attestation certificate is not verified. GNU July 3, 2023 FIDO2-CRED(1)