diff --git a/litebox/src/fs/devices.rs b/litebox/src/fs/devices.rs
index df24df2da7..ecd817a6ee 100644
--- a/litebox/src/fs/devices.rs
+++ b/litebox/src/fs/devices.rs
@@ -293,7 +293,7 @@ where
                 Ok(0)
             }
             Device::URandom => {
-                self.litebox.x.platform.fill_bytes_crng(buf);
+                self.litebox.x.platform.fill_bytes_crng(buf, None);
                 Ok(buf.len())
             }
         }
diff --git a/litebox/src/platform/mock.rs b/litebox/src/platform/mock.rs
index 5eed9f861e..4e764814b4 100644
--- a/litebox/src/platform/mock.rs
+++ b/litebox/src/platform/mock.rs
@@ -321,7 +321,7 @@ impl StdioProvider for MockPlatform {
 }
 
 impl CrngProvider for MockPlatform {
-    fn fill_bytes_crng(&self, buf: &mut [u8]) {
+    fn fill_bytes_crng(&self, buf: &mut [u8], _seed: Option<&[u8]>) {
         let mut random = self.random.lock().unwrap();
         let mut off = 0;
         while off < buf.len() {
diff --git a/litebox/src/platform/mod.rs b/litebox/src/platform/mod.rs
index 3b354a4dbd..be313cb342 100644
--- a/litebox/src/platform/mod.rs
+++ b/litebox/src/platform/mod.rs
@@ -599,7 +599,7 @@ pub trait CrngProvider {
     /// Panics if unable to fill the buffer with random bytes. This is
     /// considered a fatal error--LiteBox code is not expected to handle such
     /// failures.
-    fn fill_bytes_crng(&self, buf: &mut [u8]);
+    fn fill_bytes_crng(&self, buf: &mut [u8], seed: Option<&[u8]>);
 }
 
 /// Provider of derived device-specific keys.
diff --git a/litebox_common_lvbs/src/lib.rs b/litebox_common_lvbs/src/lib.rs
index 916cd7f33d..068dedc899 100644
--- a/litebox_common_lvbs/src/lib.rs
+++ b/litebox_common_lvbs/src/lib.rs
@@ -48,11 +48,9 @@ pub const VSM_VTL_CALL_FUNC_ID_KEXEC_VALIDATE: u32 = 0x1_ffea;
 pub const VSM_VTL_CALL_FUNC_ID_PATCH_TEXT: u32 = 0x1_ffeb;
 pub const VSM_VTL_CALL_FUNC_ID_ALLOCATE_RINGBUFFER_MEMORY: u32 = 0x1_ffec;
 
-// This VSM function ID for setting the platform root key is subject to change
-pub const VSM_VTL_CALL_FUNC_ID_SET_PLATFORM_ROOT_KEY: u32 = 0x1_ffed;
-
-// This VSM function ID for generating the identity signing key is subject to change
-pub const VSM_VTL_CALL_FUNC_ID_GENERATE_IDENTITY_SIGNING_KEY: u32 = 0x1_ffee;
+// This VSM function ID for setting the platform root key and generating the identity signing key is subject to change
+pub const VSM_VTL_CALL_FUNC_ID_SET_PLATFORM_ROOT_KEY_AND_GENERATE_IDENTITY_SIGNING_KEY: u32 =
+    0x1_ffed;
 
 // This VSM function ID for OP-TEE messages is subject to change
 pub const VSM_VTL_CALL_FUNC_ID_OPTEE_MESSAGE: u32 = 0x1_fff0;
@@ -76,8 +74,8 @@ pub enum VsmFunction {
     PatchText = VSM_VTL_CALL_FUNC_ID_PATCH_TEXT,
     OpteeMessage = VSM_VTL_CALL_FUNC_ID_OPTEE_MESSAGE,
     AllocateRingbufferMemory = VSM_VTL_CALL_FUNC_ID_ALLOCATE_RINGBUFFER_MEMORY,
-    SetPlatformRootKey = VSM_VTL_CALL_FUNC_ID_SET_PLATFORM_ROOT_KEY,
-    GenerateIdentitySigningKey = VSM_VTL_CALL_FUNC_ID_GENERATE_IDENTITY_SIGNING_KEY,
+    SetPlatformRootKeyAndGenerateIdentitySigningKey =
+        VSM_VTL_CALL_FUNC_ID_SET_PLATFORM_ROOT_KEY_AND_GENERATE_IDENTITY_SIGNING_KEY,
 }
 
 // `HV_STATUS_*` constants used as discriminants for `HypervCallError`.
diff --git a/litebox_platform_linux_kernel/src/host/snp/snp_impl.rs b/litebox_platform_linux_kernel/src/host/snp/snp_impl.rs
index cc994a2202..60ad240e55 100644
--- a/litebox_platform_linux_kernel/src/host/snp/snp_impl.rs
+++ b/litebox_platform_linux_kernel/src/host/snp/snp_impl.rs
@@ -589,7 +589,7 @@ impl HostInterface for HostSnpInterface {
 }
 
 impl litebox::platform::CrngProvider for SnpLinuxKernel {
-    fn fill_bytes_crng(&self, buf: &mut [u8]) {
+    fn fill_bytes_crng(&self, buf: &mut [u8], _seed: Option<&[u8]>) {
         // FIXME: call into the trusted host to get random bytes.
         static RANDOM: spin::mutex::SpinMutex<litebox::utils::rng::FastRng> =
             spin::mutex::SpinMutex::new(litebox::utils::rng::FastRng::new_from_seed(
diff --git a/litebox_platform_linux_userland/src/lib.rs b/litebox_platform_linux_userland/src/lib.rs
index 7006a876d0..859fe4f735 100644
--- a/litebox_platform_linux_userland/src/lib.rs
+++ b/litebox_platform_linux_userland/src/lib.rs
@@ -2341,7 +2341,7 @@ unsafe fn interrupt_signal_handler(
 }
 
 impl litebox::platform::CrngProvider for LinuxUserland {
-    fn fill_bytes_crng(&self, buf: &mut [u8]) {
+    fn fill_bytes_crng(&self, buf: &mut [u8], _seed: Option<&[u8]>) {
         getrandom::fill(buf).expect("getrandom failed");
     }
 }
diff --git a/litebox_platform_lvbs/src/host/lvbs_impl.rs b/litebox_platform_lvbs/src/host/lvbs_impl.rs
index d77c792fde..f4eae7521a 100644
--- a/litebox_platform_lvbs/src/host/lvbs_impl.rs
+++ b/litebox_platform_lvbs/src/host/lvbs_impl.rs
@@ -105,14 +105,14 @@ unsafe impl litebox::platform::ThreadLocalStorageProvider for LvbsLinuxKernel {
 }
 
 impl litebox::platform::CrngProvider for LvbsLinuxKernel {
-    fn fill_bytes_crng(&self, buf: &mut [u8]) {
+    fn fill_bytes_crng(&self, buf: &mut [u8], seed: Option<&[u8]>) {
         static RANDOM: spin::mutex::SpinMutex<Option<LvbsCrng>> = spin::mutex::SpinMutex::new(None);
 
         let mut random = RANDOM.lock();
         random
             .get_or_insert_with(|| {
                 LvbsCrng::new(
-                    PRK_ONCE.get().expect("Platform root key not initialized"),
+                    seed.expect("CRNG seed not provided"),
                     rdrand_seed().expect("RDRAND unavailable during CRNG initialization"),
                 )
             })
@@ -134,10 +134,10 @@ struct LvbsCrng {
 }
 
 impl LvbsCrng {
-    fn new(prk: &[u8; PRK_LEN], rdrand_seed: CrngSeed) -> Self {
+    fn new(seed: &[u8], rdrand_seed: CrngSeed) -> Self {
         Self {
-            random: rand_chacha::ChaCha20Rng::from_seed(crng_seed_from_prk_and_rdrand(
-                prk,
+            random: rand_chacha::ChaCha20Rng::from_seed(crng_seed_from_tpm_and_rdrand(
+                seed,
                 rdrand_seed,
             )),
             bytes_until_reseed: CRNG_RESEED_INTERVAL_BYTES,
@@ -231,10 +231,10 @@ fn rdrand_seed() -> Option<CrngSeed> {
     Some(seed)
 }
 
-fn crng_seed_from_prk_and_rdrand(prk: &[u8; PRK_LEN], rdrand_seed: CrngSeed) -> CrngSeed {
+fn crng_seed_from_tpm_and_rdrand(seed: &[u8], rdrand_seed: CrngSeed) -> CrngSeed {
     sha2::Sha256::new()
         .chain_update(b"litebox-lvbs-crng-seed-v1")
-        .chain_update(prk)
+        .chain_update(seed)
         .chain_update(rdrand_seed)
         .finalize()
         .into()
diff --git a/litebox_platform_windows_userland/src/lib.rs b/litebox_platform_windows_userland/src/lib.rs
index 2cc2740210..c488a75bb6 100644
--- a/litebox_platform_windows_userland/src/lib.rs
+++ b/litebox_platform_windows_userland/src/lib.rs
@@ -2057,7 +2057,7 @@ unsafe impl litebox::platform::ThreadLocalStorageProvider for WindowsUserland {
 }
 
 impl litebox::platform::CrngProvider for WindowsUserland {
-    fn fill_bytes_crng(&self, buf: &mut [u8]) {
+    fn fill_bytes_crng(&self, buf: &mut [u8], _seed: Option<&[u8]>) {
         getrandom::fill(buf).expect("getrandom failed");
     }
 }
diff --git a/litebox_runner_lvbs/src/lib.rs b/litebox_runner_lvbs/src/lib.rs
index 8e5350bdc5..d178aeb423 100644
--- a/litebox_runner_lvbs/src/lib.rs
+++ b/litebox_runner_lvbs/src/lib.rs
@@ -13,7 +13,7 @@ use litebox::{
     utils::{ReinterpretSignedExt, TruncateExt},
 };
 use litebox_common_linux::errno::Errno;
-use litebox_common_lvbs::{NUM_VTLCALL_PARAMS, VsmError, VsmFunction};
+use litebox_common_lvbs::{NUM_VTLCALL_PARAMS, PRK_LEN, VsmError, VsmFunction};
 use litebox_common_optee::{
     OpteeMessageCommand, OpteeMsgArgs, OpteeRpcArgs, OpteeSmcArgs, OpteeSmcResult,
     OpteeSmcReturnCode, TeeOrigin, TeeResult, UteeEntryFunc, UteeParams, optee_msg_args_total_size,
@@ -256,10 +256,24 @@ fn vtlcall_dispatch(params: &[u64; NUM_VTLCALL_PARAMS]) -> i64 {
             let smc_args_pfn = params[1];
             optee_smc_handler_entry(smc_args_pfn)
         }
-        VsmFunction::GenerateIdentitySigningKey => {
-            let public_key_pa = params[1];
-            let key_alg = params[2];
-            litebox_shim_optee::idk::generate_identity_signing_key(public_key_pa, key_alg)
+        VsmFunction::SetPlatformRootKeyAndGenerateIdentitySigningKey => {
+            let tpm_random_pa = params[1];
+            let public_key_pa = params[2];
+            let key_alg = params[3];
+
+            let return_code = vsm_dispatch(
+                VsmFunction::SetPlatformRootKeyAndGenerateIdentitySigningKey,
+                &params[1..2],
+            );
+            if return_code < 0 {
+                return return_code;
+            }
+
+            litebox_shim_optee::idk::generate_identity_signing_key(
+                tpm_random_pa + PRK_LEN as u64,
+                public_key_pa,
+                key_alg,
+            )
         }
         _ => vsm_dispatch(func_id, &params[1..]),
     }
@@ -310,9 +324,8 @@ fn vsm_dispatch(func_id: VsmFunction, params: &[u64]) -> i64 {
         VsmFunction::AllocateRingbufferMemory => {
             heki.allocate_ringbuffer_memory(params[0], params[1])
         }
-        VsmFunction::SetPlatformRootKey => vtl1.set_platform_root_key(params[0]).map(|()| 0),
-        VsmFunction::GenerateIdentitySigningKey => {
-            Err(VsmError::OperationNotSupported("Identity key generation"))
+        VsmFunction::SetPlatformRootKeyAndGenerateIdentitySigningKey => {
+            vtl1.set_platform_root_key(params[0]).map(|()| 0)
         }
         VsmFunction::OpteeMessage => Err(VsmError::OperationNotSupported("OP-TEE communication")),
     };
diff --git a/litebox_shim_linux/src/syscalls/misc.rs b/litebox_shim_linux/src/syscalls/misc.rs
index ee546e53eb..b1c4a13280 100644
--- a/litebox_shim_linux/src/syscalls/misc.rs
+++ b/litebox_shim_linux/src/syscalls/misc.rs
@@ -26,7 +26,11 @@ impl<Platform: ShimPlatform, FS: ShimFS> Task<Platform, FS> {
         while offset < count {
             let len = (count - offset).min(kbuf.len());
             let kbuf = &mut kbuf[..len];
-            <_ as litebox::platform::CrngProvider>::fill_bytes_crng(self.global.platform, kbuf);
+            <_ as litebox::platform::CrngProvider>::fill_bytes_crng(
+                self.global.platform,
+                kbuf,
+                None,
+            );
             buf.copy_from_slice::<Platform>(offset, kbuf)
                 .ok_or(Errno::EFAULT)?;
             offset += len;
diff --git a/litebox_shim_optee/src/idk.rs b/litebox_shim_optee/src/idk.rs
index 282aea63b1..558187cbe2 100644
--- a/litebox_shim_optee/src/idk.rs
+++ b/litebox_shim_optee/src/idk.rs
@@ -1,7 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 
-use crate::NormalWorldMutPtr;
+use crate::{NormalWorldConstPtr, NormalWorldMutPtr};
 use litebox::{mm::linux::PAGE_SIZE, platform::CrngProvider, utils::TruncateExt};
 use litebox_common_linux::errno::Errno;
 use num_enum::TryFromPrimitive;
@@ -11,6 +11,7 @@ use zeroize::Zeroizing;
 
 const IDENTITY_SIGNING_PRIVATE_KEY_LEN: usize = 48;
 const IDENTITY_SIGNING_PUBLIC_KEY_LEN: usize = 97;
+const TPM_IDKS_RANDOM_LEN: usize = 32;
 const KEY_ALGORITHM_MASK: u64 = 0xff00;
 const KEY_VARIANT_MASK: u64 = 0xff;
 const KEY_ALGORITHM_VALUE_MASK: u64 = KEY_ALGORITHM_MASK | KEY_VARIANT_MASK;
@@ -40,8 +41,8 @@ enum EcdsaCurve {
     P521 = 0x03,
 }
 
-pub fn generate_identity_signing_key(public_key_pa: u64, key_alg: u64) -> i64 {
-    match generate_identity_signing_key_inner(public_key_pa, key_alg) {
+pub fn generate_identity_signing_key(tpm_random_pa: u64, public_key_pa: u64, key_alg: u64) -> i64 {
+    match generate_identity_signing_key_inner(tpm_random_pa, public_key_pa, key_alg) {
         Ok(res) => res,
         Err(e) => e.as_neg().into(),
     }
@@ -61,16 +62,30 @@ pub fn generate_identity_signing_key(public_key_pa: u64, key_alg: u64) -> i64 {
 /// This function assumes that the caller prepares a buffer at the given physical
 /// address (in a single or contiguous physical memory page(s)) whose length is equal to
 /// or greater than `IDENTITY_SIGNING_PUBLIC_KEY_LEN`.
-fn generate_identity_signing_key_inner(public_key_pa: u64, key_alg: u64) -> Result<i64, Errno> {
+fn generate_identity_signing_key_inner(
+    tpm_random_pa: u64,
+    public_key_pa: u64,
+    key_alg: u64,
+) -> Result<i64, Errno> {
     validate_key_algorithm(key_alg)?;
 
+    let tpm_random_ptr = NormalWorldConstPtr::<u8, PAGE_SIZE>::with_contiguous_pages(
+        tpm_random_pa.trunc(),
+        TPM_IDKS_RANDOM_LEN,
+    )
+    .map_err(|_| Errno::EINVAL)?;
+    let mut tpm_random = [0u8; TPM_IDKS_RANDOM_LEN];
+    tpm_random_ptr
+        .read_slice_at_offset(0, &mut tpm_random)
+        .map_err(|_| Errno::EFAULT)?;
+
     let pubkey_ptr =
         NormalWorldMutPtr::<[u8; IDENTITY_SIGNING_PUBLIC_KEY_LEN], PAGE_SIZE>::with_usize(
             public_key_pa.trunc(),
         )
         .map_err(|_| Errno::EINVAL)?;
 
-    let key_pair = get_identity_signing_key_pair()?;
+    let key_pair = get_identity_signing_key_pair(Some(&tpm_random))?;
     pubkey_ptr
         .write_at_offset(0, key_pair.public_key)
         .map_err(|_| Errno::EFAULT)?;
@@ -100,9 +115,11 @@ fn validate_key_algorithm(key_alg: u64) -> Result<(), Errno> {
     }
 }
 
-fn get_identity_signing_key_pair() -> Result<&'static IdentitySigningKeyPair, Errno> {
+fn get_identity_signing_key_pair(
+    tpm_random: Option<&[u8; TPM_IDKS_RANDOM_LEN]>,
+) -> Result<&'static IdentitySigningKeyPair, Errno> {
     IDENTITY_SIGNING_KEY_PAIR.try_call_once(|| {
-        let private_key = generate_identity_signing_private_key()?;
+        let private_key = generate_identity_signing_private_key(tpm_random)?;
         let public_key = identity_signing_public_key_from_private_key(&private_key)?;
         Ok(IdentitySigningKeyPair {
             private_key,
@@ -111,12 +128,13 @@ fn get_identity_signing_key_pair() -> Result<&'static IdentitySigningKeyPair, Er
     })
 }
 
-fn generate_identity_signing_private_key()
--> Result<Zeroizing<[u8; IDENTITY_SIGNING_PRIVATE_KEY_LEN]>, Errno> {
+fn generate_identity_signing_private_key(
+    tpm_random: Option<&[u8; TPM_IDKS_RANDOM_LEN]>,
+) -> Result<Zeroizing<[u8; IDENTITY_SIGNING_PRIVATE_KEY_LEN]>, Errno> {
     let mut private_key_bytes = Zeroizing::new([0u8; IDENTITY_SIGNING_PRIVATE_KEY_LEN]);
 
     for _ in 0..MAX_KEYGEN_ATTEMPT {
-        litebox_platform_multiplex::platform().fill_bytes_crng(&mut *private_key_bytes);
+        litebox_platform_multiplex::platform().fill_bytes_crng(&mut *private_key_bytes, tpm_random.map(|r| &r[..]));
         if is_valid_identity_signing_private_key(&private_key_bytes) {
             return Ok(private_key_bytes);
         }
@@ -160,7 +178,7 @@ mod tests {
         let message = b"IDK_S signing test message";
 
         let _task = init_platform();
-        let private_key = generate_identity_signing_private_key().unwrap();
+        let private_key = generate_identity_signing_private_key(None).unwrap();
         assert!(is_valid_identity_signing_private_key(&private_key));
         let signing_key = SigningKey::from_slice(&private_key[..]).unwrap();
         let public_key = identity_signing_public_key_from_private_key(&private_key).unwrap();
diff --git a/litebox_shim_optee/src/loader/ta_stack.rs b/litebox_shim_optee/src/loader/ta_stack.rs
index a0057a78b7..5e8cb8c30c 100644
--- a/litebox_shim_optee/src/loader/ta_stack.rs
+++ b/litebox_shim_optee/src/loader/ta_stack.rs
@@ -258,7 +258,7 @@ impl TaStack {
 
         // Random 16-byte stack canary
         let mut canary = [0u8; 16];
-        <Platform as litebox::platform::CrngProvider>::fill_bytes_crng(platform, &mut canary);
+        <Platform as litebox::platform::CrngProvider>::fill_bytes_crng(platform, &mut canary, None);
         self.push_bytes(&canary)?;
 
         // `reenter_thread` *jumps* into the TA entry point (which is a function) rather than
diff --git a/litebox_shim_optee/src/syscalls/cryp.rs b/litebox_shim_optee/src/syscalls/cryp.rs
index 60394b0eae..c9f6c523c8 100644
--- a/litebox_shim_optee/src/syscalls/cryp.rs
+++ b/litebox_shim_optee/src/syscalls/cryp.rs
@@ -310,6 +310,7 @@ impl Task {
             <crate::Platform as litebox::platform::CrngProvider>::fill_bytes_crng(
                 self.global.platform,
                 buf,
+                None,
             );
         }
         Ok(())