#[non_exhaustive]
pub enum Tag {
Show 23 variants Boolean, Integer, BitString, OctetString, Null, ObjectIdentifier, Real, Enumerated, Utf8String, Sequence, Set, NumericString, PrintableString, TeletexString, VideotexString, Ia5String, UtcTime, GeneralizedTime, VisibleString, BmpString, Application { constructed: bool, number: TagNumber, }, ContextSpecific { constructed: bool, number: TagNumber, }, Private { constructed: bool, number: TagNumber, },
}
Available on crate feature pkcs8 only.
Expand description

ASN.1 tags.

Tags are the leading identifier octet of the Tag-Length-Value encoding used by ASN.1 DER and identify the type of the subsequent value.

They are described in X.690 Section 8.1.2: Identifier octets, and structured as follows:

| Class | P/C | Tag Number |
  • Bits 8/7: Class
  • Bit 6: primitive (0) or constructed (1)
  • Bits 5-1: tag number

Variants (Non-exhaustive)§

This enum is marked as non-exhaustive
Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.
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Boolean

BOOLEAN tag: 1.

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Integer

INTEGER tag: 2.

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BitString

BIT STRING tag: 3.

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OctetString

OCTET STRING tag: 4.

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Null

NULL tag: 5.

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ObjectIdentifier

OBJECT IDENTIFIER tag: 6.

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Real

REAL tag: 9.

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Enumerated

ENUMERATED tag: 10.

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Utf8String

UTF8String tag: 12.

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Sequence

SEQUENCE tag: 16.

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Set

SET and SET OF tag: 17.

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NumericString

NumericString tag: 18.

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PrintableString

PrintableString tag: 19.

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TeletexString

TeletexString tag: 20.

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VideotexString

VideotexString tag: 21.

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Ia5String

IA5String tag: 22.

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UtcTime

UTCTime tag: 23.

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GeneralizedTime

GeneralizedTime tag: 24.

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VisibleString

VisibleString tag: 26.

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BmpString

BMPString tag: 30.

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Application

Fields

§constructed: bool

Is this tag constructed? (vs primitive).

§number: TagNumber

Tag number.

Application tag.

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ContextSpecific

Fields

§constructed: bool

Is this tag constructed? (vs primitive).

§number: TagNumber

Tag number.

Context-specific tag.

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Private

Fields

§constructed: bool

Is this tag constructed? (vs primitive).

§number: TagNumber

Tag number.

Private tag number.

Implementations§

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impl Tag

pub fn assert_eq(self, expected: Tag) -> Result<Tag, Error>

Assert that this Tag matches the provided expected tag.

On mismatch, returns an Error with ErrorKind::TagUnexpected.

pub fn class(self) -> Class

Get the Class that corresponds to this Tag.

pub fn number(self) -> TagNumber

Get the TagNumber (lower 6-bits) for this tag.

pub fn is_constructed(self) -> bool

Does this tag represent a constructed (as opposed to primitive) field?

pub fn is_application(self) -> bool

Is this an application tag?

pub fn is_context_specific(self) -> bool

Is this a context-specific tag?

pub fn is_private(self) -> bool

Is this a private tag?

pub fn is_universal(self) -> bool

Is this a universal tag?

pub fn octet(self) -> u8

Get the octet encoding for this Tag.

pub fn length_error(self) -> Error

Create an Error for an invalid Length.

pub fn non_canonical_error(self) -> Error

Create an Error for an non-canonical value with the ASN.1 type identified by this tag.

pub fn unexpected_error(self, expected: Option<Tag>) -> Error

Create an Error because the current tag was unexpected, with an optional expected tag.

pub fn value_error(self) -> Error

Create an Error for an invalid value with the ASN.1 type identified by this tag.

Trait Implementations§

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impl Clone for Tag

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fn clone(&self) -> Tag

Returns a copy of the value. Read more
1.0.0 · source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for Tag

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fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more
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impl<'a> Decode<'a> for Tag

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fn decode<R>(reader: &mut R) -> Result<Tag, Error>
where R: Reader<'a>,

Attempt to decode this message using the provided decoder.
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fn from_der(bytes: &'a [u8]) -> Result<Self, Error>

Parse Self from the provided DER-encoded byte slice.
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impl DerOrd for Tag

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fn der_cmp(&self, other: &Tag) -> Result<Ordering, Error>

Return an Ordering between self and other when serialized as ASN.1 DER.
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impl Display for Tag

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fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more
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impl Encode for Tag

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fn encoded_len(&self) -> Result<Length, Error>

Compute the length of this value in bytes when encoded as ASN.1 DER.
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fn encode(&self, writer: &mut impl Writer) -> Result<(), Error>

Encode this value as ASN.1 DER using the provided Writer.
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fn encode_to_slice<'a>(&self, buf: &'a mut [u8]) -> Result<&'a [u8], Error>

Encode this value to the provided byte slice, returning a sub-slice containing the encoded message.
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fn encode_to_vec(&self, buf: &mut Vec<u8>) -> Result<Length, Error>

Available on crate feature alloc only.
Encode this message as ASN.1 DER, appending it to the provided byte vector.
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fn to_der(&self) -> Result<Vec<u8>, Error>

Available on crate feature alloc only.
Encode this type as DER, returning a byte vector.
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impl Ord for Tag

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fn cmp(&self, other: &Tag) -> Ordering

This method returns an Ordering between self and other. Read more
1.21.0 · source§

fn max(self, other: Self) -> Self
where Self: Sized,

Compares and returns the maximum of two values. Read more
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fn min(self, other: Self) -> Self
where Self: Sized,

Compares and returns the minimum of two values. Read more
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fn clamp(self, min: Self, max: Self) -> Self
where Self: Sized + PartialOrd,

Restrict a value to a certain interval. Read more
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impl PartialEq for Tag

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fn eq(&self, other: &Tag) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl PartialOrd for Tag

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fn partial_cmp(&self, other: &Tag) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
1.0.0 · source§

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
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fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
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fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
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fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl TryFrom<u8> for Tag

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type Error = Error

The type returned in the event of a conversion error.
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fn try_from(byte: u8) -> Result<Tag, Error>

Performs the conversion.
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impl Copy for Tag

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impl Eq for Tag

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impl StructuralPartialEq for Tag

Auto Trait Implementations§

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impl RefUnwindSafe for Tag

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impl Send for Tag

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impl Sync for Tag

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impl Unpin for Tag

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impl UnwindSafe for Tag

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> Same for T

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type Output = T

Should always be Self
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T> ToString for T
where T: Display + ?Sized,

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default fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> DecodeOwned for T
where T: for<'a> Decode<'a>,