[BACK]Return to PROTOCOL.certkeys CVS log [TXT][DIR] Up to [local] / src / usr.bin / ssh

Diff for /src/usr.bin/ssh/PROTOCOL.certkeys between version 1.7 and 1.8

version 1.7, 2010/08/04 05:40:39 version 1.8, 2010/08/31 11:54:45
Line 5 
Line 5 
 ----------  ----------
   
 The SSH protocol currently supports a simple public key authentication  The SSH protocol currently supports a simple public key authentication
 mechanism. Unlike other public key implementations, SSH eschews the  mechanism. Unlike other public key implementations, SSH eschews the use
 use of X.509 certificates and uses raw keys. This approach has some  of X.509 certificates and uses raw keys. This approach has some benefits
 benefits relating to simplicity of configuration and minimisation  relating to simplicity of configuration and minimisation of attack
 of attack surface, but it does not support the important use-cases  surface, but it does not support the important use-cases of centrally
 of centrally managed, passwordless authentication and centrally  managed, passwordless authentication and centrally certified host keys.
 certified host keys.  
   
 These protocol extensions build on the simple public key authentication  These protocol extensions build on the simple public key authentication
 system already in SSH to allow certificate-based authentication.  system already in SSH to allow certificate-based authentication. The
 The certificates used are not traditional X.509 certificates, with  certificates used are not traditional X.509 certificates, with numerous
 numerous options and complex encoding rules, but something rather  options and complex encoding rules, but something rather more minimal: a
 more minimal: a key, some identity information and usage options  key, some identity information and usage options that have been signed
 that have been signed with some other trusted key.  with some other trusted key.
   
 A sshd server may be configured to allow authentication via certified  A sshd server may be configured to allow authentication via certified
 keys, by extending the existing ~/.ssh/authorized_keys mechanism  keys, by extending the existing ~/.ssh/authorized_keys mechanism to
 to allow specification of certification authority keys in addition  allow specification of certification authority keys in addition to
 to raw user keys. The ssh client will support automatic verification  raw user keys. The ssh client will support automatic verification of
 of acceptance of certified host keys, by adding a similar ability  acceptance of certified host keys, by adding a similar ability to
 to specify CA keys in ~/.ssh/known_hosts.  specify CA keys in ~/.ssh/known_hosts.
   
 Certified keys are represented using two new key types:  Certified keys are represented using new key types:
 ssh-rsa-cert-v01@openssh.com and ssh-dss-cert-v01@openssh.com that  
 include certification information along with the public key that is used  
 to sign challenges. ssh-keygen performs the CA signing operation.  
   
       ssh-rsa-cert-v01@openssh.com
       ssh-dss-cert-v01@openssh.com
       ecdsa-sha2-nistp256-cert-v01@openssh.com
       ecdsa-sha2-nistp384-cert-v01@openssh.com
       ecdsa-sha2-nistp521-cert-v01@openssh.com
   
   These include certification information along with the public key
   that is used to sign challenges. ssh-keygen performs the CA signing
   operation.
   
 Protocol extensions  Protocol extensions
 -------------------  -------------------
   
Line 47 
Line 53 
 New public key formats  New public key formats
 ----------------------  ----------------------
   
 The ssh-rsa-cert-v01@openssh.com and ssh-dss-cert-v01@openssh.com key  The certificate key types take a similar high-level format (note: data
 types take a similar high-level format (note: data types and  types and encoding are as per RFC4251 section 5). The serialised wire
 encoding are as per RFC4251 section 5). The serialised wire encoding of  encoding of these certificates is also used for storing them on disk.
 these certificates is also used for storing them on disk.  
   
 #define SSH_CERT_TYPE_USER    1  #define SSH_CERT_TYPE_USER    1
 #define SSH_CERT_TYPE_HOST    2  #define SSH_CERT_TYPE_HOST    2
Line 93 
Line 98 
     string    signature key      string    signature key
     string    signature      string    signature
   
   ECDSA certificate
   
       string    "ecdsa-sha2-nistp256@openssh.com" |
                 "ecdsa-sha2-nistp384@openssh.com" |
                 "ecdsa-sha2-nistp521@openssh.com"
       string    nonce
       string    curve
       string    public_key
       uint64    serial
       uint32    type
       string    key id
       string    valid principals
       uint64    valid after
       uint64    valid before
       string    critical options
       string    extensions
       string    reserved
       string    signature key
       string    signature
   
 The nonce field is a CA-provided random bitstring of arbitrary length  The nonce field is a CA-provided random bitstring of arbitrary length
 (but typically 16 or 32 bytes) included to make attacks that depend on  (but typically 16 or 32 bytes) included to make attacks that depend on
 inducing collisions in the signature hash infeasible.  inducing collisions in the signature hash infeasible.
Line 101 
Line 126 
   
 p, q, g, y are the DSA parameters as described in FIPS-186-2.  p, q, g, y are the DSA parameters as described in FIPS-186-2.
   
   curve and public key are respectively the ECDSA "[identifier]" and "Q"
   defined in section 3.1 of RFC5656.
   
 serial is an optional certificate serial number set by the CA to  serial is an optional certificate serial number set by the CA to
 provide an abbreviated way to refer to certificates from that CA.  provide an abbreviated way to refer to certificates from that CA.
 If a CA does not wish to number its certificates it must set this  If a CA does not wish to number its certificates it must set this
Line 123 
Line 151 
 "valid after" and "valid before" specify a validity period for the  "valid after" and "valid before" specify a validity period for the
 certificate. Each represents a time in seconds since 1970-01-01  certificate. Each represents a time in seconds since 1970-01-01
 00:00:00. A certificate is considered valid if:  00:00:00. A certificate is considered valid if:
          valid after <= current time < valid before  
   
       valid after <= current time < valid before
   
 criticial options is a set of zero or more key options encoded as  criticial options is a set of zero or more key options encoded as
 below. All such options are "critical" in the sense that an implementation  below. All such options are "critical" in the sense that an implementation
 must refuse to authorise a key that has an unrecognised option.  must refuse to authorise a key that has an unrecognised option.
Line 137 
Line 166 
 the protocol.  the protocol.
   
 signature key contains the CA key used to sign the certificate.  signature key contains the CA key used to sign the certificate.
 The valid key types for CA keys are ssh-rsa and ssh-dss. "Chained"  The valid key types for CA keys are ssh-rsa, ssh-dss and the ECDSA types
   ecdsa-sha2-nistp256, ecdsa-sha2-nistp384, ecdsa-sha2-nistp521. "Chained"
 certificates, where the signature key type is a certificate type itself  certificates, where the signature key type is a certificate type itself
 are NOT supported. Note that it is possible for a RSA certificate key to  are NOT supported. Note that it is possible for a RSA certificate key to
 be signed by a DSS CA key and vice-versa.  be signed by a DSS or ECDSA CA key and vice-versa.
   
 signature is computed over all preceding fields from the initial string  signature is computed over all preceding fields from the initial string
 up to, and including the signature key. Signatures are computed and  up to, and including the signature key. Signatures are computed and
 encoded according to the rules defined for the CA's public key algorithm  encoded according to the rules defined for the CA's public key algorithm
 (RFC4253 section 6.6 for ssh-rsa and ssh-dss).  (RFC4253 section 6.6 for ssh-rsa and ssh-dss, RFC5656 for the ECDSA
   types).
   
 Critical options  Critical options
 ----------------  ----------------
Legend:
Removed from v.1.7  
changed lines
  Added in v.1.8