diff --git a/docs/src/index.md b/docs/src/index.md
index e042a9a..0797f83 100644
--- a/docs/src/index.md
+++ b/docs/src/index.md
@@ -72,6 +72,8 @@ sha2_224
 sha2_256
 sha2_384
 sha2_512
+sha2_512_224
+sha2_512_256
 ```
 
 **SHA-3**
@@ -150,6 +152,8 @@ SHA2_224_CTX
 SHA2_256_CTX
 SHA2_384_CTX
 SHA2_512_CTX
+SHA2_512_224_CTX
+SHA2_512_256_CTX
 ```
 
 **SHA-3**
diff --git a/src/SHA.jl b/src/SHA.jl
index 7aeac4b..dbc2acd 100644
--- a/src/SHA.jl
+++ b/src/SHA.jl
@@ -37,10 +37,12 @@ module SHA
 export sha1, SHA1_CTX, update!, digest!
 export sha224, sha256, sha384, sha512
 export sha2_224, sha2_256, sha2_384, sha2_512
+export sha2_512_224, sha2_512_256
 export sha3_224, sha3_256, sha3_384, sha3_512
 export shake128, shake256
 export SHA224_CTX, SHA256_CTX, SHA384_CTX, SHA512_CTX
 export SHA2_224_CTX, SHA2_256_CTX, SHA2_384_CTX, SHA2_512_CTX
+export SHA2_512_224_CTX, SHA2_512_256_CTX
 export SHA3_224_CTX, SHA3_256_CTX, SHA3_384_CTX, SHA3_512_CTX
 export SHAKE_128_CTX, SHAKE_256_CTX
 export HMAC_CTX, hmac_sha1
@@ -74,6 +76,8 @@ for (f, ctx) in [(:sha1, :SHA1_CTX),
                  (:sha2_256, :SHA2_256_CTX),
                  (:sha2_384, :SHA2_384_CTX),
                  (:sha2_512, :SHA2_512_CTX),
+                 (:sha2_512_224, :SHA2_512_224_CTX),
+                 (:sha2_512_256, :SHA2_512_256_CTX),
                  (:sha3_224, :SHA3_224_CTX),
                  (:sha3_256, :SHA3_256_CTX),
                  (:sha3_384, :SHA3_384_CTX),
diff --git a/src/constants.jl b/src/constants.jl
index 546aeee..59b24c2 100644
--- a/src/constants.jl
+++ b/src/constants.jl
@@ -1,4 +1,8 @@
-# SHA initial hash values and constants
+"""SHA initial hash values and constants
+
+Reference:
+- SHA-1, SHA2: FIPS 180-4: https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf
+"""
 
 # Hash constant words K for SHA1
 const K1 = UInt32[
@@ -104,6 +108,23 @@ const SHA2_512_initial_hash_value = UInt64[
     0x1f83d9abfb41bd6b, 0x5be0cd19137e2179
 ]
 
+# Initial hash value H for SHA-512/224
+const SHA2_512_224_initial_hash_value = UInt64[
+    0x8C3D37C819544DA2, 0x73E1996689DCD4D6,
+    0x1DFAB7AE32FF9C82, 0x679DD514582F9FCF,
+    0x0F6D2B697BD44DA8, 0x77E36F7304C48942,
+    0x3F9D85A86A1D36C8, 0x1112E6AD91D692A1
+]
+
+# Initial hash value H for SHA-512/256
+const SHA2_512_256_initial_hash_value = UInt64[
+    0x22312194FC2BF72C, 0x9F555FA3C84C64C2,
+    0x2393B86B6F53B151, 0x963877195940EABD,
+    0x96283EE2A88EFFE3, 0xBE5E1E2553863992,
+    0x2B0199FC2C85B8AA, 0x0EB72DDC81C52CA2
+]
+
+
 # Round constants for SHA3 rounds
 const SHA3_ROUND_CONSTS = UInt64[
     0x0000000000000001, 0x0000000000008082, 0x800000000000808a,
diff --git a/src/sha2.jl b/src/sha2.jl
index 0c64743..b26e8cd 100644
--- a/src/sha2.jl
+++ b/src/sha2.jl
@@ -102,10 +102,11 @@ macro R_end(T)
 end
 
 @generated function transform!(context::Union{SHA2_224_CTX, SHA2_256_CTX,
-                                              SHA2_384_CTX, SHA2_512_CTX})
+                                              SHA2_384_CTX, SHA2_512_CTX,
+                                              SHA2_512_224_CTX, SHA512_256_CTX})
     if context <: Union{SHA2_224_CTX,SHA2_256_CTX}
         T = 256
-    elseif context <: Union{SHA2_384_CTX,SHA2_512_CTX}
+    elseif context <: Union{SHA2_384_CTX,SHA2_512_CTX,SHA2_512_224_CTX,SHA512_256_CTX}
         T = 512
     end
 
diff --git a/src/types.jl b/src/types.jl
index 6bc83d2..7270425 100644
--- a/src/types.jl
+++ b/src/types.jl
@@ -44,6 +44,20 @@ mutable struct SHA2_512_CTX <: SHA2_CTX
     used::Bool
 end
 
+mutable struct SHA2_512_224_CTX <: SHA2_CTX
+    state::Vector{UInt64}
+    bytecount::UInt128
+    buffer::Vector{UInt8}
+    used::Bool
+end
+
+mutable struct SHA2_512_256_CTX <: SHA2_CTX
+    state::Vector{UInt64}
+    bytecount::UInt128
+    buffer::Vector{UInt8}
+    used::Bool
+end
+
 function Base.getproperty(ctx::SHA2_CTX, fieldname::Symbol)
     if fieldname === :state
         return getfield(ctx, :state)::Union{Vector{UInt32},Vector{UInt64}}
@@ -64,7 +78,8 @@ const SHA224_CTX = SHA2_224_CTX
 const SHA256_CTX = SHA2_256_CTX
 const SHA384_CTX = SHA2_384_CTX
 const SHA512_CTX = SHA2_512_CTX
-
+const SHA512_224_CTX = SHA2_512_224_CTX
+const SHA512_256_CTX = SHA2_512_256_CTX
 
 # SHA3 224/256/384/512-bit context structures
 mutable struct SHA3_224_CTX <: SHA3_CTX
@@ -123,6 +138,8 @@ digestlen(::Type{SHA3_256_CTX}) = 32
 digestlen(::Type{SHA2_384_CTX}) = 48
 digestlen(::Type{SHA3_384_CTX}) = 48
 digestlen(::Type{SHA2_512_CTX}) = 64
+digestlen(::Type{SHA2_512_224_CTX}) = 28
+digestlen(::Type{SHA2_512_256_CTX}) = 32
 digestlen(::Type{SHA3_512_CTX}) = 64
 
 # SHA1 and SHA2 have differing element types for the internal state objects
@@ -131,6 +148,8 @@ state_type(::Type{SHA2_224_CTX}) = UInt32
 state_type(::Type{SHA2_256_CTX}) = UInt32
 state_type(::Type{SHA2_384_CTX}) = UInt64
 state_type(::Type{SHA2_512_CTX}) = UInt64
+state_type(::Type{SHA2_512_224_CTX}) = UInt64
+state_type(::Type{SHA2_512_256_CTX}) = UInt64
 state_type(::Type{T}) where {T<:SHA3_CTX} = UInt64
 
 # blocklen is the number of bytes of data processed by the transform!() function at once
@@ -139,7 +158,8 @@ blocklen(::Type{SHA2_224_CTX}) = UInt64(64)
 blocklen(::Type{SHA2_256_CTX}) = UInt64(64)
 blocklen(::Type{SHA2_384_CTX}) = UInt64(128)
 blocklen(::Type{SHA2_512_CTX}) = UInt64(128)
-
+blocklen(::Type{SHA2_512_224_CTX}) = UInt64(128)
+blocklen(::Type{SHA2_512_256_CTX}) = UInt64(128)
 blocklen(::Type{SHA3_224_CTX}) = UInt64(25*8 - 2*digestlen(SHA3_224_CTX))
 blocklen(::Type{SHA3_256_CTX}) = UInt64(25*8 - 2*digestlen(SHA3_256_CTX))
 blocklen(::Type{SHA3_384_CTX}) = UInt64(25*8 - 2*digestlen(SHA3_384_CTX))
@@ -175,6 +195,24 @@ SHA2_384_CTX() = SHA2_384_CTX(copy(SHA2_384_initial_hash_value), 0, zeros(UInt8,
 Construct an empty SHA2_512 context.
 """
 SHA2_512_CTX() = SHA2_512_CTX(copy(SHA2_512_initial_hash_value), 0, zeros(UInt8, blocklen(SHA2_512_CTX)), false)
+"""
+    SHA2_512_224_CTX()
+
+Construct an empty SHA2_512/224 context and set the initial hash value.
+
+For the source of the initial value,
+refer to [FIPS 180-4, 5.3.6.1 SHA-512/224](https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf)
+"""
+SHA2_512_224_CTX() = SHA2_512_224_CTX(copy(SHA2_512_224_initial_hash_value), 0, zeros(UInt8, blocklen(SHA2_512_224_CTX)), false)
+"""
+    SHA2_512_256_CTX()
+
+Construct an empty SHA2_512/256 context and set the initial hash value.
+
+For the source of the initial value,
+refer to [FIPS 180-4, 5.3.6.2 SHA-512/256](https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf)
+"""
+SHA2_512_256_CTX() = SHA2_512_256_CTX(copy(SHA2_512_256_initial_hash_value), 0, zeros(UInt8, blocklen(SHA2_512_256_CTX)), false)
 
 """
     SHA3_224_CTX()
@@ -229,6 +267,8 @@ show(io::IO, ::SHA2_224_CTX) = print(io, "SHA2 224-bit hash state")
 show(io::IO, ::SHA2_256_CTX) = print(io, "SHA2 256-bit hash state")
 show(io::IO, ::SHA2_384_CTX) = print(io, "SHA2 384-bit hash state")
 show(io::IO, ::SHA2_512_CTX) = print(io, "SHA2 512-bit hash state")
+show(io::IO, ::SHA2_512_224_CTX) = print(io, "SHA2 512/224-bit hash state")
+show(io::IO, ::SHA2_512_256_CTX) = print(io, "SHA2 512/256-bit hash state")
 show(io::IO, ::SHA3_224_CTX) = print(io, "SHA3 224-bit hash state")
 show(io::IO, ::SHA3_256_CTX) = print(io, "SHA3 256-bit hash state")
 show(io::IO, ::SHA3_384_CTX) = print(io, "SHA3 384-bit hash state")
diff --git a/test/constants.jl b/test/constants.jl
index 0f11983..105940f 100644
--- a/test/constants.jl
+++ b/test/constants.jl
@@ -10,15 +10,19 @@ data_desc = ["the empty string", "the string \"test\"", "lorem ipsum",
              "0 file", "one million a's Array", "one million a's Tuple"]
 sha_types = Dict(sha1 => SHA.SHA1_CTX,
             sha2_224 => SHA.SHA2_224_CTX, sha2_256 => SHA.SHA2_256_CTX, sha2_384 => SHA.SHA2_384_CTX, sha2_512 => SHA.SHA2_512_CTX,
+            sha2_512_224 => SHA.SHA2_512_224_CTX, sha2_512_256 => SHA.SHA2_512_256_CTX,
             sha3_224 => SHA.SHA3_224_CTX, sha3_256 => SHA.SHA3_256_CTX, sha3_384 => SHA.SHA3_384_CTX, sha3_512 => SHA.SHA3_512_CTX)
 sha_funcs = [sha1,
              sha2_224, sha2_256, sha2_384, sha2_512,
+             sha2_512_224, sha2_512_256,
              sha3_224, sha3_256, sha3_384, sha3_512]
 ctxs = [SHA1_CTX,
         SHA2_224_CTX, SHA2_256_CTX, SHA2_384_CTX, SHA2_512_CTX,
+        SHA2_512_224_CTX, SHA2_512_256_CTX,
         SHA3_224_CTX, SHA3_256_CTX, SHA3_384_CTX, SHA3_512_CTX]
 shws = ["SHA1 hash state",
         "SHA2 224-bit hash state", "SHA2 256-bit hash state", "SHA2 384-bit hash state", "SHA2 512-bit hash state",
+        "SHA2 512/224-bit hash state", "SHA2 512/256-bit hash state",
         "SHA3 224-bit hash state", "SHA3 256-bit hash state", "SHA3 384-bit hash state", "SHA3 512-bit hash state"]
 
 answers = Dict(
@@ -62,6 +66,23 @@ answers = Dict(
         "e718483d0ce769644e2e42c7bc15b4638e1f98b13b2044285632a803afa973ebde0ff244877ea60a4cb0432ce577c31beb009c5c2c49aa2e4eadb217ad8cc09b",
         "e718483d0ce769644e2e42c7bc15b4638e1f98b13b2044285632a803afa973ebde0ff244877ea60a4cb0432ce577c31beb009c5c2c49aa2e4eadb217ad8cc09b"
     ],
+    sha2_512_224 => [
+        "6ed0dd02806fa89e25de060c19d3ac86cabb87d6a0ddd05c333b84f4",
+        "06001bf08dfb17d2b54925116823be230e98b5c6c278303bc4909a8c",
+        "3a312b004a593b706790a4a5b25309eb7c83efb85a4d1f0a8440e09e",
+        "283bb59af7081ed08197227d8f65b9591ffe1155be43e9550e57f941",
+        "37ab331d76f0d36de422bd0edeb22a28accd487b7a8453ae965dd287",
+        "37ab331d76f0d36de422bd0edeb22a28accd487b7a8453ae965dd287"
+    ],
+    sha2_512_256 => [
+        "c672b8d1ef56ed28ab87c3622c5114069bdd3ad7b8f9737498d0c01ecef0967a",
+        "3d37fe58435e0d87323dee4a2c1b339ef954de63716ee79f5747f94d974f913f",
+        "9423e3863ebb6f22b9464aeb873a39d757ef6b6a87c4bc55642f69052741fc43",
+        "10baad1713566ac2333467bddb0597dec9066120dd72ac2dcb8394221dcbe43d",
+        "9a59a052930187a97038cae692f30708aa6491923ef5194394dc68d56c74fb21",
+        "9a59a052930187a97038cae692f30708aa6491923ef5194394dc68d56c74fb21"
+    ],
+
     sha3_224 => [
         "6b4e03423667dbb73b6e15454f0eb1abd4597f9a1b078e3f5b5a6bc7",
         "3797bf0afbbfca4a7bbba7602a2b552746876517a7f9b7ce2db0ae7b",
diff --git a/test/runtests.jl b/test/runtests.jl
index cbd7c2f..2dd9106 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -88,6 +88,19 @@ end
     end
 end
 
+@testset "SHA-512/t" begin
+    # https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Standards-and-Guidelines/documents/examples/SHA512_224.pdf
+    @test sha2_512_224("abc") |> bytes2hex ==
+        "4634270f707b6a54daae7530460842e20e37ed265ceee9a43e8924aa"
+    @test sha2_512_224("abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu") |> bytes2hex ==
+        "23fec5bb94d60b23308192640b0c453335d664734fe40e7268674af9"
+    # https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Standards-and-Guidelines/documents/examples/SHA512_256.pdf
+    @test sha2_512_256("abc") |> bytes2hex ==
+        "53048e2681941ef99b2e29b76b4c7dabe4c2d0c634fc6d46e0e2f13107e7af23"
+    @test sha2_512_256("abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu") |> bytes2hex ==
+        "3928e184fb8690f840da3988121d31be65cb9d3ef83ee6146feac861e19b563a"
+end
+
 @testset "SHA3" begin
     @test sha3_512("0" ^ 70) |> bytes2hex ==
         "1ec3e5ebb442c09e7ab7a1ee18edfa1a9ec771ad243e3e3d65cad1730416109a0890e29f9314babd7ab018a246b2f9639af29ee09aec2352a2f94dc12a2f6109"