codesign(1) BSD General Commands Manual codesign(1)
NAME
codesign -- Create and manipulate code signatures
SYNOPSIS
codesign -s identity [-i identifier] [-r requirements] [-fv] [path ...]
codesign -v [-R requirement] [-v] [path|pid ...]
codesign -d [-v] [path|pid ...]
codesign -h [-v] [pid ...]
DESCRIPTION
The codesign command is used to create, check, and display code signa-
tures, as well as inquire into the dynamic status of signed code in the
system.
codesign requires exactly one operation option to determine what action
is to be performed, as well as any number of other options to modify its
behavior. It can act on any number of objects per invocation, but per-
forms the same operation on all of them.
codesign accepts single-character (classic) options, as well as GNU-style
long options of the form --name and --name=value. Common options have
both forms; less frequent and specialized options have only long form.
Note that the form --name value (without equal sign) will not work as
expected on options with optional values.
OPTIONS
The options are as follows:
--all-architectures
When verifying a code signature on code that has a universal
("fat") Mach-O binary, separately verify each architecture con-
tained. This is the default unless overridden with the -a
(--architecture) option.
-a, --architecture architecture
When verifying or displaying signatures, explicitly select the
Mach-O architecture given. The architecture can be specified
either by name (e.g. i386) or by number; if by number, a sub-
architecture may be appended separated by a comma. This option
applies only to Mach-O binary code and is ignored for other
types. If the path uses the Mach-O format and contains no code
of the given architecture, the command will fail. The default
for verification is --all-architectures, to verify all architec-
tures present. The default for display is to report on the
native architecture of the host system. When signing, codesign
will always sign all architectures contained in a universal Mach-
O file.
--bundle-version version-string
When handling versioned bundles such as frameworks, explicitly
specify the version to operate on. This must be one of the names
in the "Versions" directory of the bundle. If not specified,
codesign uses the bundle's default version. Note that most
frameworks delivered with the system have only one version, and
thus this option is irrelevant for them. There is currently no
facility for operating on all versions of a bundle at once.
-d, --display
Display information about the code at the path(s) given. Increas-
ing levels of verbosity produce more output. The format is
designed to be moderately easy to parse by simple scripts while
still making sense to human eyes. In addition, the -r, --file-
list, --extract-certificates, and --entitlements options can be
used to retrieve additional information.
-D, --detached filename
When signing, designates that a detached signature should be
written to the specified file. The code being signed is not modi-
fied and need not be writable. When verifying, designates a file
containing a detached signature to be used for verification. Any
embedded signature in the code is ignored.
--deep When signing a bundle, specifies that nested code content such as
helpers, frameworks, and plug-ins, should be recursively signed
in turn. Beware that all signing options you specify will apply,
in turn, to such nested content.
When verifying a bundle, specifies that any nested code content
will be recursively verified as to its full content. By default,
verification of nested content is limited to a shallow investiga-
tion that may not detect changes to the nested code.
When displaying a signature, specifies that a list of directly
nested code should be written to the display output. This lists
only code directly nested within the subject; anything nested
indirectly will require recursive application of the codesign
command.
--detached-database
When signing, specifies that a detached signature should be gen-
erated as with the --detached option, but that the resulting sig-
nature should be written into a system database, from where it is
made automatically available whenever apparently unsigned code is
validated on the system.
Writing to this system database requires elevated process privi-
leges that are not available to ordinary users.
-f, --force
When signing, causes codesign to replace any existing signature
on the path(s) given. Without this option, existing signatures
will not be replaced, and the signing operation fails.
-h, --hosting
Constructs and prints the hosting chain of a running program. The
pid arguments must denote running code (pids etc.) With verbose
options, this also displays the individual dynamic validity sta-
tus of each element of the hosting chain.
-i, --identifier identifier
During signing, explicitly specify the unique identifier string
that is embedded in code signatures. If this option is omitted,
the identifier is derived from either the Info.plist (if
present), or the filename of the executable being signed, possi-
bly modified by the --prefix option. It is a very bad idea to
sign different programs with the same identifier.
-o, --options flag,...
During signing, specifies a set of option flags to be embedded in
the code signature. The value takes the form of a comma-separated
list of names (with no spaces). Alternatively, a numeric value
can be used to directly specify the option mask (CodeDirectory
flag word). See OPTION FLAGS below.
-P, --pagesize pagesize
Indicates the granularity of code signing. Pagesize must be a
power of two. Chunks of pagesize bytes are separately signed and
can thus be independently verified as needed. As a special case,
a pagesize of zero indicates that the entire code should be
signed and verified as a single, possibly gigantic page. This
option only applies to the main executable and has no effect on
the sealing of associated data, including resources.
-r, --requirements requirements
During signing, indicates that internal requirements should be
embedded in the code path(s) as specified. See "specifying
requirements" below. Defaults will be applied to requirement
types that are not explicitly specified; if you want to defeat
such a default, specify "never" for that type.
During display, indicates where to write the code's internal
requirements. Use -r- to write them to standard output.
-R, --test-requirement requirement
During verification, indicates that the path(s) given should be
verified against the code requirement specified. If this option
is omitted, the code is verified only for internal integrity and
against its own designated requirement.
-s, --sign identity
Sign the code at the path(s) given using this identity. See SIGN-
ING IDENTITIES below.
-v, --verbose
Sets (with a numeric value) or increments the verbosity level of
output. Without the verbose option, no output is produced upon
success, in the classic UNIX style. If no other options request
a different action, the first -v encountered will be interpreted
as --verify instead (and does not increase verbosity).
-v, --verify
Requests verification of code signatures. If other actions
(sign, display, etc.) are also requested, -v is interpreted to
mean --verbose.
--continue
Instructs codesign to continue processing path arguments even if
processing one fails. If this option is given, exit due to oper-
ational errors is deferred until all path arguments have been
considered. The exit code will then indicate the most severe
failure (or, with equal severity, the first such failure encoun-
tered).
--dryrun
During signing, performs almost all signing operations, but does
not actually write the result anywhere. Cryptographic signatures
are still generated, actually using the given signing identity
and triggering any access control checks normally, though the
resulting signature is then discarded.
--entitlements path
When signing, take the file at the given path and embed its con-
tents in the signature as entitlement data. If the data at path
does not already begin with a suitable binary ("blob") header,
one is attached automatically.
When displaying a signature, extract any entitlement data from
the signature and write it to the path given. Use "-" to write to
standard output. By default, the binary "blob" header is
returned intact; prefix the path with a colon ":" to automati-
cally strip it off. If the signature has no entitlement data,
nothing is written (this is not an error).
--extract-certificates prefix
When displaying a signature, extract the certificates in the
embedded certificate chain and write them to individual files.
The prefix argument is appended with numbers 0, 1, ... to form
the filenames, which can be relative or absolute. Certificate 0
is the leaf (signing) certificate, and as many files are written
as there are certificates in the signature. The files are in
ASN.1 (DER) form. If prefix is omitted, the default prefix is
"codesign" in the current directory.
--file-list path
When signing or displaying a signature, codesign writes to the
given path a list of files that may have been modified as part of
the signing process. This is useful for installer or patcher pro-
grams that need to know what was changed or what files are needed
to make up the "signature" of a program. The file given is
appended-to, with one line per absolute path written. An argument
of "-" (single dash) denotes standard output. Note that the list
may be somewhat pessimistic - all files not listed are guaranteed
to be unchanged by the signing process, but some of the listed
files may not actually have changed. Also note that changes may
have been made to extended attributes of these files.
--ignore-resources
During static validation, do not validate the contents of the
code's resources. In effect, this will pass validation on code
whose resources have been corrupted (or inappropriately signed).
On large programs, it will also substantially speed up static
validation, since all the resources will not be read into memory.
Obviously, the outcome of such a validation should be considered
on its merits.
--keychain filename
During signing, only search for the signing identity in the key-
chain file specified. This can be used to break any matching ties
if you have multiple similarly-named identities in several key-
chains on the user's search list. Note that the standard key-
chain search path is still consulted while constructing the cer-
tificate chain being embedded in the signature.
Note that filename will not be searched to resolve the signing
identity's certificate chain unless it is also on the user's key-
chain search list.
--prefix string
If no explicit unique identifier is specified (using the -i
option), and if the implicitly generated identifier does not con-
tain any dot (.) characters, then the given string is prefixed to
the identifier before use. If the implicit identifier contains a
dot, it is used as-is. Typically, this is used to deal with com-
mand tools without Info.plists, whose default identifier is sim-
ply the command's filename; the conventional prefix used is
com.domain. (note that the final dot needs to be explicit).
--preserve-metadata=list
When re-signing code that is already signed, reuse some informa-
tion from the old signature. If new data is specified explic-
itly, it is preferred. You still need to specify the -f
(--force) option to enable overwriting signatures at all. If
this option is absent, any old signature has no effect on the
signing process.
This option takes a comma-separated list of names, which you may
reasonably abbreviate:
identifier Preserve the signing identifier (--identifier)
instead of generating a default identifier.
entitlements Preserve the entitlement data (--entitlements).
resource-rules Preserve and reuse the resource rules
(--resource-rules).
requirements Preserve the internal requirements (--require-
ments option), including any explicit Designated
Requirement. Note that all internal requirements
are preserved or regenerated as a whole; you can-
not pick and choose individual elements with this
option.
For historical reasons, this option can be given without a value,
which preserves all of these values as presently known. This use
is deprecated and will eventually be removed; always specify an
explicit list of preserved items.
--resource-rules filename
During signing, this option overrides the default rules for iden-
tifying and collecting bundle resources and nested code to be
sealed into the signature. The argument is the path to a property
list (plist) file containing scanning and qualification instruc-
tions. See the code signing documentation for details.
--timestamp [=URL]
During signing, requests that a timestamp authority server be
contacted to authenticate the time of signing. The server con-
tacted is given by the URL value. If this option is given with-
out a value, a default server provided by Apple is used. Note
that this server may not support signatures made with identities
not furnished by Apple. If the timestamp authority service can-
not be contacted over the Internet, or it malfunctions or refuses
service, the signing operation will fail.
If this option is not given at all, a system-specific default
behavior is invoked. This may result in some but not all code
signatures being timestamped.
The special value none explicitly disables the use of timestamp
services.
OPERATION
In the first synopsis form, codesign attempts to sign the code objects at
the path(s) given, using the identity provided. Internal requirements and
entitlements are embedded if requested. Internal requirements not speci-
fied may be assigned suitable default values. Defaulting applies sepa-
rately to each type of internal requirement. If an identifier is explic-
itly given, it is sealed into all path(s). Otherwise, each path derives
its identifier independently from its Info.plist or pathname. Code
nested within bundle directories (as identified from the applicable
Resource Rules) must already be signed or the signing operation will
fail, unless the --deep option is given, in which case any unsigned
nested code will be recursively signed before proceeding, using the same
signing options and parameters. If the --force option is given, any
existing top-level signature is replaced, subject to any
--preserve-metadata options also present. Combining the --force and
--deep options results in forcible replacement of all signatures within
the target bundle, as long as the resource rules identify them.
In the second synopsis form, codesign verifies the code signatures on all
the path(s) given. The verification confirms that the code at those
path(s) is signed, that the signature is valid, and that all sealed com-
ponents are unaltered. If a requirement is given, each path is also
checked against this requirement (but see DIAGNOSTICS below). If verbose
verification is requested, the program is also checked against its own
designated requirement, which should never fail for a properly signed
program.
If a path begins with a decimal digit, it is interpreted as the process
id of a running process in the system, and dynamic validation is per-
formed on that process instead. This checks the code's dynamic status
and just enough static data to close the nominal security envelope. Add
at least one level of verbosity to also perform a full static check.
In the third synopsis form, codesign displays the contents of the signa-
tures on the path(s) given. More information is displayed as the ver-
bosity level increases. This form may not completely verify the signa-
tures on the path(s); though it may perform some verification steps in
the process of obtaining information about the path(s). If the -r path
option is given, internal requirements will be extracted from the path(s)
and written to path; specify a dash "-" to write to standard output. If
the code does not contain an explicit designated requirement, the implied
one will be retrieved and written out as a source comment. If the
--entitlements path option is given, embedded entitlement data will be
extracted likewise and written to the file specified.
In the fourth synopsis form, codesign constructs the hosting path for
each pid given and writes it, one host per line, to standard output. The
hosting path is the chain of code signing hosts starting with the most
specific code known to be running, and ending with the root of trust (the
kernel). If the --verbose option is given, the dynamic validity status of
each host is also displayed, separated from the path by a tab character.
Note that hosting chains can at times be constructed for invalid or even
unsigned code, and the output of this form of the codesign command should
not be taken as a statement of formal code validity. Only codesign
--verify can do that; and in fact, formal verification constructs the
hosting chain as part of its operation (but does not display it).
SIGNING IDENTITIES
To be used for code signing, a digital identity must be stored in a key-
chain that is on the calling user's keychain search list. All keychain
sources are supported if properly configured. In particular, it is possi-
ble to sign code with an identity stored on a supported smart card. If
your signing identity is stored in a different form, you need to make it
available in keychain form to sign code with it.
If the --keychain argument is used, identity is only looked-for in the
specific keychain given. This is meant to help disambiguate references to
identities. Even in that case, the full keychain search list is still
consulted for additional certificates needed to complete the signature.
The identity is first considered as the full name of a keychain identity
preference. If such a preference exists, it directly names the identity
used. Otherwise, the identity is located by searching all keychains for
a certificate whose subject common name (only) contains the identity
string given. If there are multiple matches, the operation fails and no
signing is performed; however, an exact match is preferred over a partial
match. These comparisons are case sensitive. Multiple instances of the
exactly same certificate in multiple keychains are tolerated as harmless.
If identity consists of exactly forty hexadecimal digits, it is instead
interpreted as the SHA-1 hash of the certificate part of the desired
identity. In this case, the identity's subject name is not considered.
Both identity preferences and certificate hashes can be used to identify
a particular signing identity regardless of name. Identity preferences
are global settings for each user and provide a layer of indirection.
Certificate hashes are very explicit and local. These choices, combined
with what is placed into Xcode project and target build variables and/or
script settings, allows for very flexible designation of signing identi-
ties.
If identity is the single letter "-" (dash), ad-hoc signing is performed.
Ad-hoc signing does not use an identity at all, and identifies exactly
one instance of code. Significant restrictions apply to the use of ad-hoc
signed code; consult documentation before using this.
codesign will attempt to embed the entire certificate chain documenting
the signing identity in the code signature it generates, including any
intermediate certificates and the anchor certificate. It looks for those
in the keychain search list of the user performing the signing operation.
If it cannot generate the entire certificate chain, signing may still
succeed, but verification may fail if the verifying code does not have an
independent source for the missing certificates (from its keychains).
SPECIFYING REQUIREMENTS
The requirement(s) arguments (-r and -R) can be given in various forms. A
plain text argument is taken to be a path to a file containing the
requirement(s). codesign will accept both binary files containing prop-
erly compiled requirements code, and source files that are automatically
compiled before use. An argument of "-" requests that the requirement(s)
are read from standard input. Finally, an argument that begins with an
equal sign "=" is taken as a literal requirements source text, and is
compiled accordingly for use.
OPTION FLAGS
When signing, a set of option flags can be specified to change the behav-
ior of the system when using the signed code. The following flags are
recognized by codesign; other flags may exist at the API level. Note that
you can specify any valid flags by giving a (single) numeric value
instead of a list of option names.
kill Forces the signed code's kill flag to be set when the code
begins execution. Code with the kill flag set will die when it
becomes dynamically invalid. It is therefore safe to assume that
code marked this way, once validated, will have continue to have
a valid identity while alive.
hard Forces the signed code's hard flag to be set when the code
begins execution. The hard flag is a hint to the system that
the code prefers to be denied access to resources if gaining
such access would invalidate its identity.
host Marks the code as capable of hosting guest code. You must set
this option if you want the code to act as a code signing host,
controlling subsidiary ("guest") code. This flag is set automat-
ically if you specify an internal guest requirement.
expires Forces any validation of the code to consider expiration of the
certificates involved. Code signatures generated with this flag
will fail to verify once any of the certificates in the chain
has expired, regardless of the intentions of the verifier. Note
that this flag does not affect any other checks that may cause
signature validation to fail, including checks for certificate
revocation.
Note that code can set the hard and kill flags on itself at any time. The
signing options only affect their initial state. Once set by any means,
these flags cannot be cleared for the lifetime of the code. Therefore,
specifying such flags as signing options guarantees that they will be set
whenever the signed code runs.
If the code being signed has an Info.plist that contains a key named
CSFlags, the value of that key is taken as the default value for the
options. The value of CSFlags can be a string in the same form as the
--options option, or an integer number specifying the absolute numeric
value. Note however that while you can abbreviate flag names on the com-
mand lines, you must spell them out in the Info.plist.
EXAMPLES
To sign application Terminal.app with a signing identity named "author-
ity":
codesign -s authority Terminal.app
To sign the command-line tool "helper" with the same identity, overwrit-
ing any existing signature, using the signing identifier
"com.mycorp.helper", and embedding a custom designated requirement
codesign -f -s authority --prefix=com.mycorp. -r="designated =>
anchor /tmp/foo" helper
To verify the signature on Terminal.app and produce some verbose output:
codesign --verify --verbose Terminal.app
To verify the dynamic validity of process 666:
codesign --verify 666
To display all information about Terminal.app's code signature:
codesign --display --verbose=4 Terminal.app
To extract the internal requirements from Terminal.app to standard out-
put:
codesign --display -r- Terminal.app
DIAGNOSTICS
codesign exits 0 if all operations succeed. This indicates that all codes
were signed, or all codes verified properly as requested. If a signing or
verification operation fails, the exit code is 1. Exit code 2 indicates
invalid arguments or parameters. Exit code 3 indicates that during veri-
fication, all path(s) were properly signed but at least one of them
failed to satisfy the requirement specified with the -R option.
For verification, all path arguments are always investigated before the
program exits. For all other operations, the program exits upon the
first error encountered, and any further path arguments are ignored,
unless the --continue option was specified, in which case codesign will
defer the failure exit until after it has attempted to process all path
arguments in turn.
SIGNING ATOMICITY
When a signing operation fails for a particular code, the code may
already have been modified in certain ways by adding requisite signature
data. Such information will not change the operation of the code, and the
code will not be considered signed even with these pieces in place. You
may repeat the signing operation without difficulty. Note however that a
previous valid signature may have been effectively destroyed if you spec-
ified the -f option.
If you require atomicity of signing stricter than provided by codesign,
you need to make an explicit copy of your code and sign that.
ENVIRONMENT
If the CODESIGN_ALLOCATE environment variable is set, it identifies a
substitute codesign_allocate tool used to allocate space for code signa-
tures in Mach-O binaries. This is used by Xcode SDK distributions to pro-
vide architectural support for non-native platforms such as iPhones. The
system will not accept such substitutes unless they are specially signed
(by Apple).
FILES
/var/db/DetachedSignatures System-wide database of detached code signa-
tures for unsigned code.
SEE ALSO
csreq(1), xcodebuild(1), codesign_allocate(1)
HISTORY
The codesign command first appeared in Mac OS 10.5.0 (Leopard).
BUGS
Some options only apply to particular operations, and codesign ignores
them (without complaining) if you specify them for an operation for which
they have no meaning.
The --preserve-metadata option used to take no value, and varied across
releases in what exactly it preserved. The ensuing confusion is still
with you if you need to make backward-compatible scripts.
The dual meaning of the -v option, indicating either verbosity or verifi-
cation, confuses some people. If you find it confusing, use the unambigu-
ous long forms --verbose and --verify instead.
NOTES
The Xcode build system invokes codesign automatically if the
CODE_SIGN_IDENTITY build variable is set. You can express any combina-
tion of codesign options with additional build variables there.
codesign is fundamentally a shell around the code signing APIs, and per-
forms nothing of the underlying work. Replacing it with older or newer
versions is unlikely to have a useful effect.
codesign has several operations and options that are purposely left
undocumented in this manual page because they are either experimental
(and subject to change at any time), or unadvised to the unwary. The
interminably curious are referred to the published source code.
BSD May 7, 2011 BSD
Mac OS X 10.9 - Generated Sat Oct 12 09:37:51 CDT 2013