Class: SSHPublicKey

Inherits:
Object
  • Object
show all
Defined in:
lib/ssh-publickey.rb,
lib/ssh-publickey/version.rb

Overview

Convert SSH public key from/to RFC4716/OpenSSH format

Defined Under Namespace

Classes: PublicKeyError

Constant Summary collapse

LINE_BREAK =

Maximum text size in a line for PEM format

70
AUTHORIZED_KEY_REGEX =

Regex for authorized key

/^(?:    (?<directives>(?:[!-~]|\s(?=.*"))+) \s+ )?   # Options
        (?<type>      [a-z0-9_-]+)          \s+      # Type
        (?<key>       [A-Za-z0-9+\/]+=*)             # Key
 (?:\s+ (?<comment>.*?)                     \s* )?   # Comments
$/x
PUBKEY_OPENSSH_REGEX =

Regex for OpenSSH public key Same as authorized keys but without directives

/^       (?<type>   [a-z0-9_-]+)             \s+      # Type
        (?<key>    [A-Za-z0-9+\/]+=*)                # Key
 (?:\s+ (?<comment>.*?)                     \s* )?   # Comments
$/x
PUBKEY_RFC4716_REGEX =

Regex for RFC4716 public key

/^----\sBEGIN\sSSH2\sPUBLIC\sKEY\s----\R
 (?<tags> (?:[^:\p{Space}\p{Cntrl}]{1,64}            # Tags
             \s*:\s*
             (?:[^\\\r\n]*\\\R)* [^\\\r\n]+\R)*)
 (?<key>  (?:[A-Za-z0-9+\/]+\R)*                     # Key
          [A-Za-z0-9+\/]+=*\R)
 ----\sEND\sSSH2\sPUBLIC\sKEY\s----
$/xmu
PUBKEY_RFC4716_HEADERTAG_REGEX =

:nodoc:

/[^:\p{Space}\p{Cntrl}]{1,64}
\s*:\s*   
(?:[^\\\r\n]*\\\R)*[^\\\r\n]+\R/xmu
VERSION =

Current version

'0.1'

Class Method Summary collapse

Class Method Details

.is_openssh?(pubkey) ⇒ Boolean

Test if a public key is in OpenSSH format

Parameters:

  • pubkey (String) —

    public key in RFC4716 format

Returns:

  • (Boolean) 


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# File 'lib/ssh-publickey.rb', line 117

def self.is_openssh?(pubkey)
    PUBKEY_RFC4716_REGEX.match?(pubkey)
end

.is_rfc4716?(pubkey) ⇒ Boolean

Test if a public key is in RFC4716 format

Parameters:

  • pubkey (String) —

    public key in RFC4716 format

Returns:

  • (Boolean) 


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# File 'lib/ssh-publickey.rb', line 128

def self.is_rfc4716?(pubkey)
    PUBKEY_RFC4716_REGEX.match?(pubkey)
end

.openssh_to_rfc4716(pubkey) ⇒ String

Convert a public key in OpenSSH format to RFC4716 format

Parameters:

  • pubkey (String) —

    public key in OpenSSH format

Returns:

  • (String) —

    public key in RFC4716 format



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# File 'lib/ssh-publickey.rb', line 58

def self.openssh_to_rfc4716(pubkey)
    unless m = AUTHORIZED_KEY_REGEX.match(pubkey)
        raise PublicKeyError, "invalid OpenSSH public key"
    end

    # Lines are limited to 72 8-bytes char
    #  - limit ourselves to 70 to keep room for \\ and \n
    #  - comment part can be unicode so 1 char can be more that 1 byte
    linesize = 0
    comment  = "Comment: #{m[:comment]}"
                  .each_char.slice_before {|c|
                       bytesize = c.bytes.size 
                       if linesize + bytesize > LINE_BREAK
                       then linesize  = 0        ; true
                       else linesize += bytesize ; false
                       end
                  }.map(&:join).join("\\\n")
    key      = m[:key].scan(/.{1,70}/).join("\n")
    
    reskey   = []
    reskey   << "---- BEGIN SSH2 PUBLIC KEY ----"
    reskey   << comment
    reskey   << key
    reskey   << "---- END SSH2 PUBLIC KEY ----"
    reskey.join("\n")
end

.rfc4716_to_openssh(pubkey) ⇒ String

Convert a public key in RFC4716 format to OpenSSH format

Parameters:

  • pubkey (String) —

    public key in RFC4716 format

Returns:

  • (String) —

    public key in OpenSSH format



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# File 'lib/ssh-publickey.rb', line 92

def self.rfc4716_to_openssh(pubkey)
    unless m = PUBKEY_RFC4716_REGEX.match(pubkey) 
        raise PublicKeyError, "invalid RFC4716 public key"
    end

    key        = m[:key].gsub(/\R/, '')
    keydata    = m[:key].unpack1('m')
    len        = keydata.unpack1('N')
    type       = keydata[4,len]
    tags       = Hash[m[:tags].scan(PUBKEY_RFC4716_HEADERTAG_REGEX)
                              .map {|tag| tag.gsub(/\\\R/, '').strip }
                              .map {|tag| tag.split(/\s*:\s*/, 2)    }]
    comment    = tags.transform_keys {|k| k.downcase }['comment']
    directives = nil
    
    [directives, type,  key, comment ].compact.join(' ')
end